Underwater Demolition Training at Eniwetok

Underwater Demolition Training at Eniwetok
July-August 26, 1944

Excerpts from the personal wartime journal of
Sergeant Patrick L. Finelli
U.S. Marine Corps

Capt. Sweet volunteered himself, me and another Marine for a special assignment. I was a good swimmer, trained in bomb disposal and demolitions. We were dispatched to Eniwetok where we learned how to use a mask and fins along with Navy OSS personnel. Captain Sweet was relatively old at this time (late 30’s), a reserve officer, and I never saw him in the water, so his role is unclear to me. At Eniwetok, we were given physicals, swim tests, cots and tents. Our trainers were introduced as being OSS. I did not know who they were, what they did or where they went when finished. We were in a small group of Marines, Fleet volunteers and Army Engineers.

We were indoctrinated to swim fins (Churchill) and face masks by Navy OSS trainers. We experimented with “Shot-loads” to destroy CB built obstacles. It was very serious, deadly and surprisingly quiet – not much conversation at all. Capt. Sweet never participated, he just observed and took notes. Although it was explained that prior demolition training was preferable, it wasn’t essential and could be taught. It would be easier to teach explosives than swimming. A higher priority was placed on swimming ability (i.e. a strong swimmer comfortable in open water). Much time was spent testing for panic levels when stressed and it was surprising to see very good swimmers lose it despite clear visibility in 60 ft straight down when seen through a 5″ diameter Sea Dive Mask. The best advice we got was to stay calm, slow everything down, don’t get scared. We were taught to swim sidestroke, trudgeon and breast strokes, turning our heads to the side to minimize mask reflections. We used the crawl stroke for emergencies and/or extractions.

The explosives we used were a mix of what happened to be available such as 1 lb. and ½ lb. blocks of TNT, Comp. C-3, 60% dynamite, tetryl and tetrytol. We had 10, 30 & 100 cap blasting machines (called Hell Boxes). We also had Primacord, blasting caps (electric and natural), safety fuse with length formulas and calculations, delayed tetryl caps and percussion caps. We learned how to set charges in checkerboard and center patterns, how to waterproof connections and most importantly, team integrity and paired buddy dependence. We also had some very good classroom instruction in Amphibious Landing Operations; mission and organization of combat demolition units, methods and techniques. All in all, an intensive training program in eliminating man-made and natural underwater obstructions. We are now ready for whatever assignments await us.

What a marvelous addition to my Marine training. All the elements of discipline, brotherhood and preparedness are evident and expected to be employed soon. At the conclusion of training, were broke up and went different ways. Our group was assigned to the Clemson, APD-31, a converted World War I vessel. We did not know our final destination – Peleliu.

Editor’s note: Eniwetok may have been a “top-secret” training base for UDTs. It was the scene of the first operations of UDT Teams 1 and 2, according to accounts in The Men from Fort Pierce by Marvin Cooper. UDT recon and Marine landings took place in January, 1944, effectively ending enemy control of the Marshalls and its “three fortified strongholds,” Kwajalein, Roi-Namur, and Eniwetok. Eniwetok was an ideal place to set up a secret UDT training base for strong swimmers and ordnance experts, in full operation by the summer of 1944.