The first officially acknowledged U-Boat attack by a United States Navy vessel was the ‘Greer Incident’ on 4th September 1941, when the USS Greer dropped depth charges after believing a U-Boat had attempted to torpedo her. The United States was still neutral at this time but the U.S. Navy was taking an increasingly active role in escorting convoys in co-ordination with the Royal Navy.
According to Wolfgang Hirschfield, who kept a secret diary of his time as radio-telegraphist on board U-109, the first attack may well have been some months before that. On the 16th May 1941 a hydrophone sweep detected a ‘battle group’ close by to U-109. The U-Boat surfaced in thick fog and prepared four torpedo tubes for attack. It cruised for a few minutes before the fog cleared a little, giving “a misty view of of the battle masts of a large naval unit dead ahead”:
Emergency orders were bellowed out and the boat heeled violently as the diesels were thrown to full ahead and the helm was put to port, bringing her broadside to the swell, the exhaust outlets spluttering as the sea swept across them.
The Captain yelled down for even more revolutions and the diesels began to hammer furiously, plunging the bows deeply into each wave; then the alarm bells rang and the watch came tumbling down to land in a heap on the control room grating. Fischer slammed the tower hatch lid shut as the submarine went down at a steep angle. Through the loudspeakers the calm voice of the boatswain, Maureschat, ordered the bow caps closed and stated the trim depth as 180 feet.
I asked him what was going on and he said that as far as he knew we had been spotted.
Lt Keller joined me in the hydrophones room. ‘They’re Americans,’ he whispered. ‘The mist got patchy suddenly and I saw their typical bar-masts. We turned away at once, but one of the destroyer escort made towards us.’
‘Bearing?’ asked the Captain from the control room. ‘Destroyer at 190°,’ I called back, and then continued in a low voice to the Lieutenant, ‘If they’re Americans, they can’t touch us.’ Keller cast me a pitying look. ‘You’re soon going to find out.’
U-109 was turning to port while the destroyer was approaching fast overhead from astern, her propellers thrashing at a tremendous speed.
‘Full ahead.’ ‘Take the hydrophones off,’ Keller told me, ‘we can all hear him now.’ The men in the control room were all staring at the deckhead as though there was something to be seen there. A few seconds after the escort vessel had cleared us there was a somewhat muted explosion in the sea some distance abeam and the shock wave rolled the submarine once or twice.
‘Are you sure these are Americans?’ I asked Keller. ‘Certainly. I got a glimpse of the battleship myself for a moment. An old type, Arizona or New York, but definitely not British.’