U-157 sank the Hagan in the Old Bahama Channel but was tracked down and sunk off Key West a few days later

Diagrams and schematic of the Type IXC German U-boat, of which U-157 was one.

Source: http://www.uboat.net/types/ixc.htm

            Next into the region was Wolf Henne in command of U-157. He entered the area in a line going straight west on the 6th of June 1942, rounded Turks & Caicos on the 10th and transited the Caicos Passage just east of Inagua that day for the Old Bahama Channel. U-157 proceeded up the coast of Cuba for three days, its progress being tracked by US and Cuban forces via radio and from volunteer Pan American and a US Navy aircraft on the 10th of June.

              On the 11th he sank the 6,401 US molasses tanker Hagan five miles north of Cuba near Cape Roman and Cayo Verde (Green Cay). It was to be the only tanker sunken by either the skipper or the boat in their respectively “green” careers. Later on the same day a US B 18 bomber spotted the boat and dropped four depth charges (Wynn, Vol. 1, p.121).

            As a result of the Hagan sinking and other tracking inputs, by the time the submarine reached the new US anti-submarine base off Key West Florida on the 13th it was attacked and sunk by seven depth charges from the USS Thetis, a destroyer under Lt. N. C. McCormick, and a pack of other Allied vessels in a determined and systematic attack. It was the second U-boat sunk on a patrol to the region after Rostin in U-158 met its demise off Bermuda some weeks before.

             Wolf Henne sailed to the Bahamas as an officer in the German merchant marine before the war. Born in Futschau, China (where Germany maintained a colony and naval base in Tsingtao) in 1905, he was 36 years of age when killed by the Allied hunter-killer group hastily organized for the task. A member of the Crew of 1924, in 1939 Henne had been given the rank Korvettenkapitän – he received no promotions or decorations in the intervening three years of his life.

             The sinking of U-157 underscores the stark fact that most U-boats or their commanders were lost on first or early patrols. Unlike the vast majority of U-boats which attacked the region that were on their third, fourth of fifth war patrols, U-157 and her commander were relatively untested in combat, having experienced only a short eleven-day patrol before its final one, which only lasted 27 days. Normally a submarine would go on several forays into convoys in the North Atlantic or the region west of Biscay before setting off on trans-Atlantic missions of long duration.

SOURCES: Gudmundur Helgason, Rainer Kolbicz, www.uboat.net, 2011m Kenneth Wynn, U-boat Operations of the Second World War, Volume 1 and Volume 2, 1997