B-18A Bolo formation on anti submarine patrol
A typical anti-submarine patrol during World War II was a rigorous and often monotonous routine, focused on detecting and deterring German U-boats from attacking Allied shipping. These missions, flown primarily in B-18 bombers, were essential in maintaining control over vital sea lanes, though they were fraught with challenges, from weather conditions to the limitations of technology.
Pre-Mission Briefing
Before dawn, the crew would gather for a briefing led by the Operations Officer. This meeting covered navigation charts, radio and visual signals, reports of U-boat activity, and the positions of Allied and enemy vessels. The Met Officer provided a weather briefing, emphasizing the importance of radio silence unless absolutely necessary. The crew, typically consisting of a pilot, co-pilot, bombardier, radar operator (if equipped), navigator (though often absent due to shortages), and crew chief (who doubled as the gunner), would prepare for the mission. They dressed in coveralls, life vests, and carried essential gear like a pistol, knife, and canteen. The aircraft was equipped with emergency supplies, including rubber life rafts, a Tommy Gun, and smoke bombs.
Takeoff and Patrol
After pre-flight checks, the aircraft would receive clearance from the control tower and take off, typically in wet conditions due to tropical rains. The B-18 would climb to a cruising altitude of about 1,000 feet at a speed of 135 mph. The patrol often started at sunrise, with the pilot engaging the autopilot and the crew beginning their visual search for U-boats. Before the advent of radar, these searches were mostly futile, as U-boats would submerge at dawn to avoid detection. However, the mere presence of patrolling aircraft helped keep U-boats submerged, reducing their chances of attacking during daylight.
Weather and Search Conditions
The Caribbean’s notorious weather, especially during the rainy season, added to the difficulty of these missions. The B-18’s aging infrastructure, including leaky windows, often left the crew perpetually wet. Patrols were frequently conducted under heavy cloud cover and rain squalls, with visibility severely restricted. U-boat captains often exploited these conditions to surface and recharge batteries, relying on lookouts and listening devices to detect approaching aircraft. When a U-boat was spotted, the pilot would dive at full throttle, but often arrived too late, with the submarine already in a crash dive.
Challenges of Detection and Attack
Early in the war, without radar, detecting and attacking U-boats was extremely challenging. The aircraft had to fly directly over a U-boat to spot it, and even then, the success rate of attacks was low. Frustration often led crews to drop depth charges on the bubbling wake of a diving U-boat, though this rarely resulted in a successful hit. Tactics like “baiting,” where the aircraft would leave the area and return after some time in hopes of catching the U-boat resurfacing, were employed, but with limited success.
Return to Base
After about three hours of patrolling, covering approximately 400 miles, the aircraft would turn back toward base. The final leg was often the most hazardous, with heavy rain squalls and low clouds complicating landfall. Navigational errors could be deadly, especially with base anti-aircraft gunners instructed to fire at any aircraft not approaching from the correct direction. Despite these risks, the 45th Bombardment Squadron (45BS) remarkably lost only one aircraft to navigational error out of over 1,000 patrols.
Post-Mission Debriefing
Upon returning to base, the crew would debrief with the Squadron Operations Officer and Intelligence Officer. The details from the patrol, including sightings of Allied shipping, debris, and possible U-boat activity, were logged and sent to Navy Intelligence for analysis.
Night Patrols
Night patrols followed a similar routine but were even more challenging due to limited visibility. Early in the war, these patrols were only effective during moonlit nights. However, with the introduction of Air-to-Surface Vessel (ASV) radar, night operations became more productive, allowing patrols to continue even on dark, cloudy nights. Despite this technological advancement, the majority of patrols resulted in hours of fruitless searching, leading to frustration among the crews.
Psychological and Strategic Impact
Though many patrols ended without detecting a U-boat, the psychological impact on U-boat crews and the strategic importance of keeping them submerged and away from convoys was significant. The experience gained by the B-18 crews during these patrols would later prove invaluable as many transitioned to flying B-29s, contributing directly to the eventual Allied victory in the war.