1. MAY 1942
Part I: The Situation
1. The Second Phase of the U-boat Offensive
With the decline of U-boat success along the U.S. East Coast from the last half of April 1942, the subsequent indications the U.S. Navy might have finally begun concentrating ships into convoys forced German Admiral Karl Dönitz, commanding the U-boat arm, to make decisions as to what to do next. It stood to reason that if American defenses had been strengthened on one front, then their defenses must be weak on another. And that weak point must be the Gulf of Mexico, where no U-boats had yet operated heretofore. Up until now, the Gulf of Mexico and Yucatan Channel had been untouched by the war because of their remoteness. The Gulf of Mexico alone was almost nine hundred miles wide from Key West to the coast of Mexico. However, the use of U-tankers now made these areas accessible despite the fact that they were as much as 4000 miles from the French ports. With a large force of U-boats now at his disposal, the circumstances were right for Dönitz to employ them to open up the Gulf of Mexico and adjacent waters as a second front against the United States. If he was correct, he could expect to find the same conditions of weak defenses and vulnerable shipping here that had prevailed along the U.S. East Coast in the first months of 1942.
Accordingly, for the beginning of May 1942, Dönitz planned to send 16 to 18 U-boats for a major “frontal attack” on the U.S. East Coast from Maine to Florida. At the same time, he also planned to open this second front by sending a further nine U-boats into the Caribbean and the Gulf of Mexico. Refueling from a U-tanker would make possible the operations in these remote areas during May, not only for the long-range Type IX boats but also for Type VII boats as well. Previously, it would not have been possible to send Type VII boats deep into the Florida Straits or Gulf of Mexico and back with enough fuel to conduct any significant operations. Even though only one U-tanker, U-459, was operational during late April and early May, seven boats would be refueled from the tanker for operations in the Caribbean and Gulf. Some of the boats destined to operate in these remote areas would be topped up with fuel on the outward voyage, while others were refueled on the return trip with just enough fuel to reach home. In the case of U-753, the first Type VII boat to conduct a patrol in the Gulf of Mexico, the boat was refueled on both the outbound and return trips.
Thus began the second phase of the U-boat offensive against the United States with the exploitation of the Gulf of Mexico and the northwestern Caribbean sector of the Gulf Sea Frontier as a second front. Compared to the barren prospects off the U.S. East Coast during May, the boats that went to the Gulf of Mexico and northwestern Caribbean had excellent success. It was clearly evident the antisubmarine defenses that had been instituted by the U.S. Navy on the East Coast had not yet been extended to these waters. There were no formal convoys to be found here and no concentrations of patrol vessels and aircraft to the degree that was found off the East Coast. Ships still sailed independently across the Gulf and Caribbean, which made easy picking for the U-boats. Conditions here were comparable to those that had existed off the East Coast in the early months of the war. There was quite a stark contrast to the success that U-boats were able to achieve in these waters as opposed to the rather dismal prospects being encountered off the East Coast. As a result, Admiral Dönitz, ever the opportunist, redirected six of the boats off the East Coast to the Caribbean and Gulf of Mexico during mid-May.1 Four additional boats in the process of crossing the ocean to the U.S. coast were similarly diverted en route to the same area. Operations in the Gulf of Mexico did bring about a point for the Germans to consider. U-boats here would certainly encounter ships of Central and South American countries in the Gulf and the Florida Straits. While most of these countries had already declared war on the Axis powers, a few of these countries with active merchant fleets (Chile, Argentina, Uruguay, Brazil, and Mexico) were neutral. However, at the conclusion of the Pan-American Foreign Ministers Conference at Rio de Janeiro on January 28, 1942, all Latin American countries except Argentina and Chile adopted a recommendation to break diplomatic ties with the Axis powers and align themselves with the Allies. This included neutral Uruguay, Brazil, and Mexico. As such, if there was clear evidence of their ships trading at an enemy port, they were fair game for attack despite their professed neutrality. The Germans were also aware that Brazil and possibly other Latin American neutrals were arming their merchant ships for protection. This clearly was a war-like gesture that compromised neutrality. On May 16, the German Naval High Command (Oberkommando der Marine, or OKM) issued orders that all Latin American vessels found to be armed were to be sunk, with the exception of ships from Argentina and Chile.2 2. The Continuation of Problems for the Gulf Sea Frontier
The “frontal attack” of German Admiral Dönitz in May brought U-boats ranging along the full length of the U.S. East Coast into the waters of both the Eastern and Gulf Sea Frontiers. The Gulf Sea Frontier was hit particularly hard. Not only was the entire eastern coast of Florida now exposed to U-boat attack, but more U-boats also came prowling into the previously untouched Gulf of Mexico and northwest Caribbean at the same time. Up until May 1942, the Gulf Sea Frontier had largely escaped the destruction to shipping meted out by U-boats in the Eastern Sea Frontier. In the months leading up to May, only three U-boats and one Italian submarine had visited the Gulf Sea Frontier. Two U-boats had operated there in February, sinking five ships. Another had operated there in April, sinking two more ships. The Italian submarine had sunk two ships. That was all about to change now.
The defensive forces available to meet the U-boat threat along the Florida east coast were largely inadequate to handle the May U-boat offensive. Their struggles have been recounted in Volume 1 of this study. For the simultaneous opening of the second front of U-boat operations in the Gulf of Mexico and northwest Caribbean, the forces available for defense were even fewer in numbers. Consequently, the U-boats operating in these sectors were to experience a continuation of their “Second Happy Time” at the expense of frontier shipping.
It will be remembered that the Gulf Sea Frontier comprised three main areas: the eastern coast of Florida below Jacksonville and part of the Bahamas, the entire Gulf of Mexico, and part of the northwest end of the Caribbean Sea extending down below Cuba to the 18° 05' latitude line. The Gulf of Mexico alone was a massive area to defend. It was about 900 miles long and 450 miles wide at its narrow midpoint between the Mississippi Passes and the Yucatan Peninsula. It embraced the western coast of Florida, the Gulf Coast states, the eastern coast of Mexico, and the northwestern coast of Cuba. There were two entrances to the Gulf of Mexico: the lower Florida Straits and the Yucatan Channel.
The Caribbean sector of the frontier was also a sizeable area to defend and highly vulnerable due to its remoteness from the rest of the frontier. U-boats could easily reach this area by entering the Windward or Mona Passages through the Antilles and sweeping around the southern coast of Cuba. The large volume of ship traffic passing through this area between the Yucatan Channel, Caribbean ports, and the Panama Canal offered a target that U-boats would certainly not overlook.
These three huge frontier areas, encompassing hundreds of thousands of square miles, were a challenge to defend against enemy naval operations even under the best of conditions. The best of conditions, of course, simply did not exist for the Gulf Sea Frontier in May 1942. The frontier was forced to concentrate most of its limited resources to defend the east coast of Florida and the Florida Straits. Here, the large volume of ship traffic passing to or from the U.S. East Coast, Old Bahama/Nicholas/Santaren Channels, or Gulf of Mexico was squeezed into the very narrow pathway through the Florida Straits and its approaches. As U-boat attacks began against this traffic at the beginning of May, most of the meager surface warships of the frontier were concentrated there for defense. What was left for most of the Gulf of Mexico was the handful of warships of the Eighth Naval District: the 125-foot Coast Guard cutters Boutwell and Woodbury, the patrol yacht Onyx, and some YPs. These patrolled the sea lanes along the Gulf Coast. The warships of the East Coast Sound School at Key West could be called upon to assist in patrolling the Gulf in emergencies, but most of their attention was directed to the fighting on the Florida east coast. There were no surface warships available to be assigned to the Caribbean sector. However, it might be possible to call upon temporary assistance of warships from the adjacent Caribbean or Panama Sea Frontiers in emergency. Also, any navy warships passing through the Gulf or Caribbean sectors to other assignments might be temporarily diverted for emergencies or search and rescue.
The air defense of the Gulf and Caribbean sectors was equally lacking. Navy Fleet Air detachments...