CAPT Zeke Zellmer: Submarine Warfare

Ken Harbaugh:

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Warriors in Their Own Words is our attempt to present an unvarnished, unsanitized truth of what we have asked of those who defend this nation. Thank you for listening, and by doing so, honoring those who have served.

Today, we’ll hear from Captain Zeke Zellmer. Zellmer served as a Communications Officer aboard the USS Cavalla during WWII, and fought in the Battle of the Philippine Sea, the largest carrier-to-carrier battle in history. During the battle, the Cavalla destroyed one of Japan’s two main aircraft carriers, the Shokaku.

Captain Zeke Zellmer:

In 1939, I was in engineering school at the University of Wisconsin extension in Milwaukee and studied to be an electrical engineer. When the first awareness I had was a headline in the newspaper, “Squalus sunk.” And from that point on, you sought every source of news you could, the radio primarily, to try to keep up with what was going on. It was just an area in which I had a personal interest at that point. But it was sparse. I was in the Midwest, this was not New London.

I guess even back then, though I didn't realize it, I was interested in submarine. I had read an earlier book about the recovery of one of our S boats that was lost and I had been fascinated by it. And then during the Squalus event, you were sort of glued to the radio. We didn't have TV. So we were all following as best we could how these people might be rescued. And there was a tremendous feeling of wonder and awe when in fact they brought up a large number of the crew. And that was probably, well, that was the first time that had been accomplished.

Then there was a long ordeal thereafter of bringing the boat up. And that too made news along the way in bits and pieces and it was a fascinating story. So we just waited for the next one or went to the movie and saw movie tone news showing some scenes of rigging the big floats that they were going to try to raise the Squalus with.

And I guess it influenced me in a different way. When it came around time at the Naval Academy to decide what service you wanted to go in, I opted for submarines for oh, three reasons. First reason was that they were carrying the war to the Japanese and that I wanted to do. The second reason was as an ensign on a small ship, I would have some real responsibility rather than being a number 16 on some battleship. And as it was, I ended up as radar communication sonar officer on the Cavalla department head. The third reason relates a little bit to the Squalus. I had seen enough of the damaged individuals from World War I, who suffered through life from wounds that I felt going into the submarine service, I'd either come back whole or not at all, and it was part of my fundamental reason.

We were fortunate during World War II, lots of people wanted to get into submarines for different reasons, but the main one was that the submarine was carrying the war to the Japanese at the time, while our surface forces in the beginning of the war were rebuilding in order to be able to carry the battle to the final conclusion. So lots of people wanted to get into submarines. The force was selective. They wouldn't take people unless they had the qualifications that they were seeking. We took exams, including psychological because not only did you have to be able to do your job and know your technical requirements, but you had to get along and live with 80 other people in a confined space for two months or more at a time. And that can be kind of wearing on the occasion. So we were very, very selective. And if somebody didn't shape up, it was a simple matter. Your commanding officers would write in the man's jacket disqualified for submarines, and he was gone. So I think we had a double ended filter. We were very careful in screening and we were very positive in pushing people out of the service that didn't belong there.

Skill levels went from essentially a seaman striker who had no technical skills. It was a fresh caught apprentice, had been sent through sub school and that was all he had. All the way up to radar technicians who had to keep the radar gear going, which was a highly technical job in an era when nobody knew anything about radar.

My whole lectures on radar at the Naval Academy, which was so secret at the time, was a total of two hours just before graduation. And on my first submarine, I'm the radar officer. So it's a difficult situation when you have to have skills in engines. We had 1600 horsepower diesel engines, four of them. We had all the electrical transmissions that had to be made from the generators to the batteries to the auxiliary power supplies. So your electricians had to know all about their systems. The torpedoes and gunnery officers, here are very important specialties. The reason you're out there, your torpedoes, if you can't make that torpedo work, you better go home. Radiomen, we had technically this radar, sonar. The technical requirements were high, but that didn't apply to everybody. There were individual groups with top level skills at the top of each group going down to strikers at the bottom.

bout one in four submariners didn't return from patrol. The large bulk of those were due to enemy action. There may or may not have been a few that were lost because of other accidental causes. I know of at least one where they ran on a reef, but they got back because another boat picked them up. So enemy action was the cause of the high danger rate. You got to realize how vulnerable a submarine is. First of all, on the surface it's a pretty weak duck. We did have a five inch 25 at the end of the war. It started out with a four inch 50 gun, some 20 millimeters too, and later a 40. But that's pretty small when you start talking about anything from a DE or larger size and the guns that can be brought to bear. And that's not your first training, your gunnery. You're a low platform, it's a wobbly platform, it's not a gun platform, so you don't want to be caught on the surface. But if you have one hole in your pressure hull, you are now a surface ship, period. There is no way that you can dive again. That hole can be caused by a depth charge breaking a valve fitting. It can be caused by a shell penetrating if you're caught on the surface. Any of those things make a submarine very, very vulnerable. In ordinary operations, every dive is a potential danger. If something goes wrong during a dive, somebody makes a mistake, opens a valve when they shouldn't have, you could lose all the boat.

When you charge batteries, hydrogen gases are evolved. Anybody lighting a cigarette at the wrong place in the wrong time can end up with a hydrogen explosion. Even though you duct the batteries to the ventilation system and you watch them with hydrogen meters and so on, there's always that potential danger.

Matter of fact, we threw one boy off the boat because he tried to clean his shoes in the after battery compartment. His method of cleaning shoes was he had a lot of caked polish on him, so he put lighter shoe fluid on the shoes and lit it off, during a battery charge in the battery compartment. He was off that boat and gone within the hour. You couldn't afford a mistake, stupid or otherwise, because there was just too much at risk.

Cavalla was launched in New London, and less than a year later commissioned. And commissioning took place on the 29th of February. For sailor's superstitious reasons, we felt that the 29th of February was very auspicious and would bring luck to our lady, our lady, the Cavalla. The first patrol certainly bore that out. We had three major opportunities. Succeeded in one to do damage to the enemy, so we felt we really were on the lucky lady. The luckiest sub in the fleet… I don't know that that's anything that we talked about at the time. But certainly when we got back from our patrols, we knew that the Cavalla was one of the luckiest subs in terms of survival.

Every submarine had to have an insignia. And being a communications officer, the skippers said, "Zeke, Cavalla needs an insignia. Get one." So I started a little research to find out what a Cavalla was. What kind of a fish? It was a tropical fish. South American waters, primarily, Central America. So that to me said Spanish. Spanish said sombrero. So we have a beginning. Had to be warlike, so I put a torpedo under the fin to make it fierce because the Cavalla was an edible fish, not one of the eaters of fish. Skipper approved the idea. Being an engineer, I couldn't draw it with a T-square and triangle, so I turned to our yeoman, Rozelli. He was very talented and he came up with our original insignia, which survived skipper's approval.

In New London Day made us cuts so that we could get stationary printed and so on, and that then was our symbol. No flag. After our third patrol, I received a package from a girlfriend back in the States, and in that package was the Cavalla flag. She had taken our symbol, done it on either silk or nylon, I'm still not sure which, sewn it up and there it was. And so when we came back from our next patrol, that flag flew as Cavalla's battle flag and that's its origin.

The first battle of the Philippines Sea was precipitated because the US forces were going to go into the Marianas and retake Guam, Saipan, and Tinian from the Japanese. And so the fleet was assembled to make that invasion.mThe Japanese were concerned about that action. They were aware of the assembly of the fleet through their own air reconnaissance arm. And so they began to move their forces, which were then west of the Philippines, and they were west of the Philippines because that's where the oil supply was. And oil was short in Japan because of the loss of the submarine sinking their tankers. Therefore, it was imperative from our forces' standpoint to know where the Japanese fleet was and where it was moving and when the engagement which ultimately would happen would take place. Submarines were put at San Bernardino Straits, which was one of the egress points through the Philippines, expecting the Japs to move through there.

The Cavalla was on its way to San Bernardino to relieve the Flying Fish who was present when the Japanese mobile force came through San Bernardino straits. So that was the first report that the Japs were seriously moving now to engage the US forces. And this was just before the 15th, the actual landings on Saipan and Tinian.

The Flying Fish was the first one to make the sighting. Now the task force when it moves at say 20 knots, that's 20 sea miles an hour, is going quite rapidly. And you've got to know where that force is if you're going to engage it. So it was imperative that US forces be aware of where the Japanese were going.

Our forces were particularly concerned that they did not come in behind them and make the invasion more difficult. So submarines were put in a line to find the Japanese forces. The second force was coming around the southern end of the Philippines. The Cavalla made contact with a couple of tankers who were being escorted by three destroyers.

They tried to make an attack, but one of the destroyers detected the Cavalla and she aborted the attack in order to survive. That was reported to comm sub pack and we were then told to follow the tankers because they were concerned that they were doing a rendezvous with the fleet. And if you knew where the tankers were, you'd find the fleet.

We chased the tankers, but they were going as fast as we could and finally we were put back in a scouting line. The next day, now we're talking about the 17th of June, Cavalla saw some ships, heard some noises submerged, and found themselves with a mobile force coming at them. Ideal situation for a submarine commander, sink them all. However, the orders were report first, shoot second. And so Cavalla had to submerge quietly, let the whole fleet go by, count the ships, and then when the destroyers finally had left surface and report the location of the force. So here we were, two opportunities gone, no target sunk. Frankly the crew and the officers as well were devastated. Here we had the ideal target on our first patrol. We counted at least 15 ships by sonar. We had seen some seven ships including carriers and cruisers, and we just sat there as quietly as we could, listened to them, and let them go. This is an opportunity of lifetime. No one expected ever again to have that opportunity. And the skipper had to keep his own secrets to himself. He couldn't reveal that Saipan was about to be invaded. He was the only one aboard who knew. The rest of us were out there on patrol as if it were an ordinary patrol. So there was terrible disappointment. Morale was probably at the lowest ever I saw it on the Cavalla.

Nevertheless, we surfaced after the last destroyer left the scene and made our report and were directed to a new location. This was the morning of the so-called turkey shoot of the Marianas, the 19th of June. About the time that some of the planes were coming back to the carriers, Cavalla found another force coming over the horizon.

This time we had been forced to dive three times in the morning because of airplanes. The fourth time we dove, we saw four planes, small planes circling, so we headed in that direction. Shortly thereafter, we heard screws, so there were ships out there, obviously an aircraft carrier and was taking planes aboard. They came over the horizon, and now the important thing to know was are they Japanese or are they American? The last thing we wanted to do was to sink an American carrier. We had to know where our forces were, but we didn't. That was never revealed to us. So it is imperative that we have a positive identification before we went in and had made our final attack. We presumed they were Japanese because of where we were, but we weren't sure, so we moved on into an attack position.

Skipper was so concerned with identification that he asked the exec to take a look. The exec thumbed through the recognition manual. Then the torpedo data computer officer was given a look and still nothing positive. The Shōkaku was unlike most Japanese carriers, it had a large island on the deck, as do our carriers. Most of the other Japanese carriers were more flush deck. And so we had the one that was the easiest to confuse with an American carrier.

The quartermaster got a look. I was sitting back as a plotting officer in the aster into the conning room and the conning tower. And I was jealous of all their opportunities because I was the only one that didn't get to see it.

We're now getting closer to the target and we're going to have to make a decision. Skipper raises the scope, takes another observation. We're now close enough, the ensign stands out and he says, "There's a meatball on the ensign, it's Japanese. We'll fire on the next observation." So scope went down. We proceeded for the next three minutes, raised the scope fired three, fired six torpedoes at 1200 yards. Three of them hit the Shōkaku. Took two and a half hours to sink and was well away from our area when she did.

But meanwhile, the Japanese destroyers were giving us a bad time. We took over that two and a half hour period, 106 depth charges. The first ones were critical because the destroyer that was on the screen on our side was only 1500 yards away from us when we fired. As we went deep, we got down to about 75 feet, the destroyer went right over our stern. The first four depth charges were very, very loud. Too close. They resulted, we think, and I say we think because we didn't find the damage mechanism later, but the result was that the main induction was flooded. The main induction is the big trunk that takes air when you're on the surface and brings it down to the two engine rooms and gives the engines all the air they need and is also the boat's ventilation. So we're talking about a trunk that's 36 inches in diameter at its largest end before it tapers down, and is probably in the neighborhood of 100, 120 feet long. So we were about 12 to 15 tons heavy at that point and that's a lot of weight for a submarine. Instead of being able to go down to our test depth, which was 312 feet then, we ended up at 400 feet before we were able to control our depth and claw our way back up. We had to do that by putting a large up angle on the boat to sort of plane our way up and have the propellers push us up, if you will. And that meant having to increase our speed and our noise and so we were a better target because of the noise we were making.

But we managed to cut back up, safe depths. And our tactic was to try to attract the destroyers as they came in on their depth charge runs, keep our stern pointed toward them to give them the minimum silhouette, so that they would have just as little area as possible for them to echo range off. In addition, the screws would make the water a little bit mushy and the bearings wouldn't be quite as sharp. And then at the last minute as they were getting close, we would turn away from the track that they were on, so that we would in fact increase our hope for escape from the depth charges themselves.

As I say, it went on for about two and a half hours and then we heard four very large explosions in the distance. These were not depth charges because they continued to rumble. It was an explosion and a lot of noise. And we thought that spelled the end of the carrier, but we couldn't be sure we didn't see it. However, when we finally got back in after a run, it was clear that we had sunk the carrier and it had taken two and a half hours to go down even though it had three torpedo hits.

Contact with enemy ships is something that occurs technically really. It may be by radar, it may be by sonar, it may be by periscope. Or occasionally on the surface it can be eyeballs from the lookouts of the officer of the deck. But what you see is a silhouette on the horizon of a small ship, it looks small because it's far away. You don't visualize that ship as having people necessarily. You visualize that ship as your target and you go through the technical requirements to get into a position that you can attack that ship. That's your mission, sink enemy ships.

So in some cases, no one but the captain sees the target. Certainly in submerged attacks, that's the rule. If you happen on a surface, you'll have the captain, the office of the deck, the junior officer of the deck, and three lookouts that will be up there as observers. But at surface attacks, you're further away. If you get within 3500 yards or so at night, you're likely to be seen by the target just as you can see it.

Submarine has an advantage in that it has a small silhouette. The surface ship is much larger and you see it at a greater distance. And when you attack, you minimize your silhouette by keeping your bow as close to the enemy's direction as you can to minimize what he can see. And then of course your paint was camouflaged to make you blend into the horizon. On the surface, we were a light blue gray, so that we would look more like the horizon in the sky. The horizontal surfaces, which would be seen when you were submerged looking down, were black so that you would be like the depths of the ocean. So a submarine is a small, hard to see target. In a typical end around situation, you might be 20,000 yards away. And getting into position to attack and you could see the target because you've had your periscope raised, so you had a high point of view. But all the target you gave to the enemy was a thin scope and at 20,000 yards, that's nothing. So you never came to grips in a person to person relationship.

We all hated the Japanese at that point. We'd heard all the atrocities. And as war ended, they turned out to be true. So there were emotions that you didn't really think about in the attack. You were busy with your job, whatever it was. Mine was plotting officer, later diving officer, and I was very busy making sure that my part of the action was done and done right. And that was true of everybody aboard. Everybody had a task at battle stations. So I would say that unless you did a battle surface, and we did one against a small Sampan trawler, you never saw an individual. And if an individual had been seen, it would've been only by the skipper probably anyway.

Submarines safety lies in depth. Being able to submerge in three dimensions makes the enemy's fire control problem that much more difficult. If you know what his limitations on depth are, he can only go to 300 feet like my boat, all you have to do is operate your depth charges in that first 300 feet of water and you will have contained what he can do.

Early in the war, the Chicago Tribune in an article mentioned the actual depth that submarines were capable of going at that time. And they did it in the context that the Japanese are setting their depth charges too early. They, they're not coming down and we're able to get below them. Well, when that security vanishes, the submarines learned to shut up. And I think that that probably more than anything else, was what made us be very, very quiet about our capabilities, and above all about our limitations. You didn't want your enemy to know your weaknesses.

When we talk about World War II submarines, and that's my era, we're talking about a surface ship that could submerge. When we were submerged, we were partially blind. We could not see optically. We couldn't use radar submerged except at very shallow depth when we stick the mast up. And so we were operating with one sound domain, sound itself, sonar. In order to know where we're going, we had a gyro compass that told us our heading. We kept very careful track of the turn count of the propellers because that would tell us ultimately how fast we were going. That we did have a pit log that measured the speed directly by the pressure passed the pedo tube. So we could plot ourselves in what we called a dead reckoning track based on course and speed. If you went on course 0, 0, 0 north for an hour at 10 knots and you didn't do 10 knots submerged, you would've gone 10 miles. The best we could do submerged was about nine knots, and at the end of an hour we would've had a dead battery and that would've been the end of our submerged experience. So we normally went much slower than that in order to make the battery last longer.

When you were tracking a target, you would periodically come up to periscope depth, take a bearing on the target optically, and there was within the periscope an optical range finder, so the skipper could in fact get a range on the target. To do that, we had to estimate the height of the target because the optical range finder operated on the principle that a split lens would lower the top of the mast down to the waterline. And if you knew what that height was, the split lens was measuring the angle between the two, you could then compute what its range was and that was done mechanically by the range finder on the scope. So you'd get a range and a bearing to your target at that point. And you'd know where you were so that my job in the conning tower was then to plot where the target was. I would have my own track going along on the plotting table. And I would put a range and a bearing line out from that position that we'd taken our observation and there was the first point where the target was.

A few minutes later, giving the target time to move and ourself time to get closer, we would take another observation. And I would again plot the range and bearing from this new position that I projected on my table to the target. And now by measuring the distance between those two points for the target, I could get the distance he traveled in the time between our observations. The line between them also was the bearing or course line for that target, so I would get a course and bearing for the target for those two observations.

Now the observations were not precise. So what you needed was a series of them that you could smooth out the track and make a better approximation of what really was happening, rather than taking two points and saying, "That's it." Normally, in addition, your life would be complicated because the target would be zigging. You would go on a course for a while and then make a drastic change, move off to a different course for a period and change again. And what you were interested in, in trying to get to an attack position is what course and speed he was making over the ground? Which averaged out his zigs so that you could get ahead of him and hopefully be in position to attack. Meanwhile, if you were very fortunate and were able to use the radar, your ranges, which would be much more precise, and so your estimate of the target's course and speed would be more precise.

In the case of the Shōkaku, which we talked about earlier, they were bringing in their planes. And therefore they were on a steady course and a steady speed in order to make the landing of their aircraft more easily. And so it was fortunate the first two plots I made, first two positions, I gave an estimate of 24 knots any course. And our final estimate after we had a series of observations and had smoothed out my plotting, was 25 knots and the same course that we'd started with. That says that the captain's observations were remarkably good.

Sonar's the most difficult because it doesn't give you precise ranges or bearings. The range is more precise than the bearing. But with the submarine, we didn't use the sonar to range with until the last moment. Because if we had used the sonar in an active mode, sending out a ping, measuring the return, and getting a range, we would've alerted the target to the fact that we were there.

So all we did on our sonar normally was listen until we were ready to shoot. And then if conditions warranted, we would take a quick single ping range, enter that and fire our torpedoes and get it on the way. The bearings sonar wise, if you were within 10 or 15 degrees, most of the time you were doing reasonably well. If you were within five degrees, you were doing very well. And of course the ranges were more limited in sonar. We did not have sonar that gave us the same long ranges that radar or optical observation did.

The scope gives you a very precise bearing. The range is the thing that's difficult to estimate. But let's remember when we're talking about periscopes and observation, the longer the periscope is up there, the more assurance you have that the enemy has had a chance to spot you. And so periscope observations would normally be limited to something like 10 or 15 seconds. Up, take your observation, make a quick sweep, put it down. Always had to make a quick sweep because you didn't want to have a surprising destroyer coming over your stern quarter that you didn't see because you were absorbed on the target.

The angle on the bow is actually the least accurate information of range bearing angle on the bow. It's totally an estimate. Each ship will have a different appearance as it's coming at you. Particularly carriers are hard to judge because they don't have a nice narrow bow. You got a broad flight deck and that's what you normally see before you get to see the stem. And it's hard to estimate when you see a straight line front of the flight deck becoming a straight line, the side of the flight deck, estimating what that angle of the bow is. It's a very important observation, particularly when you don't have time for something else.

If you have time to plot a number of observations to get course and speed, you do it by plotting, as I've described earlier. If you have to estimate quickly, your first estimate will be an angle on the bow to give you an idea of what course they are on, so that you can move yourself into a position to attack. And even more important, when you've made your torpedo firing and the destroyers are coming at you, that angle on the bow can be very, very mean if it looks to be zero. So it gives you quick information but not precise information.

When we were talking about plotting the track of the target, you're plotting not only the track of the target but your own, and you're doing a relative solution. You don't care where that target is physically in the world. You only care that it's so many 1000 yards from you and burying such and such and going in such and such a direction. And so what you're trying to do is get a relative solution rather than a totally artificial arbitrary one. It's a simple matter to plot your course and speed. You set down your grid lines on a piece of paper and you put your inputs of your position, the bearing to the target, the range to the target, giving his position relative to you. Then you move your course line along as you move through the water.

And when you get another observation from that new position of your own boat, you draw another bearing line and a range line to the target and now you have two positions for that target. And so it's just a matter of a graphical solution. If you had to do it mathematically, writing an equation for it, better you had a computer, which we didn't have in those days.

Interviewer:

Okay.

Zellmer:

So graphical solutions work out as an easy, though less accurate than the mathematical solution. The torpedo data computer did the mathematical solution, giving you not only the course and speed of the target, but also told you what offset angle you should be firing at from point A to hit the target when it gets to point B sometime later. So you had what was a mechanical computer in those days, our torpedo data computer, rather than today's electronic computer.

Submarine going on patrol would be assigned an area in which it was to operate. That was done to keep other submarines out of your way and you out of their way. You were generally free to operate in that area as you thought best, unless second guessing from Pearl said, "We understand something's coming through, get over here and do something about it." So when you're searching an area, unless you're close to the coast, you can see much more of the area by being on the surface. So we would stay on the surface all day if possible, making standard speed 15 knots or so to cover a large area looking for targets. If we were close into the coast where we might be observed, then we would submerge during the day. Always had to charge batteries, so we had to come up sometime and usually at night to do our battery charge. So ordinarily at night you were always on the surface. I suppose in terms of the five patrols I was on Cavalla, the submerged time would amount to 15% of the time total, if that.

A battery charge would take anywhere from six to 10 hours generally depending upon how much of the battery you deleted. Had you used it a lot during the day and therefore had drawn it down or not? So you'd put your battery on charge at a high rate. And then you would taper it down to a lower rate as the battery charge began to come up. When we had a fully charged battery and we were going to be submerged for a maximum period of time, we would obviously creep along at its very slow speed, two knots, and we probably had enough battery for about 48 hours at that operation. We began to have as much as anything else, a CO2 buildup problem by then, and we'd have to use absorbent to get rid of some of the CO2.

We might have to bleed some extra air into the boat from the air pressure bottles in the banks, so that we had a little more oxygen left. But by the time time we were down nearly 24 hours, you couldn't light a match anymore. Smoking was impossible because a cigarette wouldn't stay lit. The oxygen depletion was that bad. Lots of our people in submarines ended up with lung problems because of the bad air and the conditions under which we lived.

Year 2000 hindsight is very good. Back in World War II time, everybody knew cigarettes were bad for you. No question. But how bad was everybody else except you. So I think that we all underestimated grossly. And smoking was regulated in terms of when the smoking lamp was lit and when it wasn't. Never at battle station, never during a battery charge. And if you knew you were going to be down for a long period, you'd put the smoking lamp out.

Ken Harbaugh:

That was CAPT Zeke Zellmer.

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