The U-507 patrol in the Caribbean was in 1942 not 1941.
I was at Utapao airbase in Thailand where the rescue operation was launched. 23 of the 39 troops lost were lost in a helicopter crash delivering Air Force security policemen to Utapao from an inland base. The island they attacked did not hold the merchant seamen. Last, communication in Cambodia was bad. The Cambodians agreed to release the seamen before the attack. 39 lives were lost to save 39.