Black May (21 page)

The course of Convoy ONS.5 and the positions of U-boat patrol lines.
Star, Specht,
and
Amsel
are shown on the German grid chart. Nautical positions courtesy of Jürgen Rohwer.
Cartographer: Paul Pugliese

It was a good night’s work, and Gretton was elated. Against what he estimated were “five or six” U-boats the
B7
team had performed splendidly. Not a single ship in the convoy had been sunk or damaged. But he was sure that the U-boats had suffered, and he was right: of the four boats that actually participated in the attacks, two, U
-386
(Oblt.z.S. Hans-Albrecht Kandler) and U
-528
(Oblt.z.S. Georg von Rabenau) were heavily damaged and forced to withdraw to base, though it is not possible to determine whether it was
Duncan
or one of the corvettes,
Sunflower
or
Snowflake,
that was responsible for either or both. The Type VIIC U
-386
limped into home port at St.-Nazaire on II May. On the same day, the Type IXC/40 U
—528,
also struggling to return from what was her first combat patrol, was approaching the Bay of Biscay when she was bombed by Halifax II “D” of 58 Squadron and finished off by H.M.S.
Fleetwood
and
Mignonette
, escorting convoy OS.47, with the loss of eleven killed, forty-five captured.
³¹
Gretton certainly thought he had a kill on the third U-boat attempt, which he called “an accurate attack,” and this may have caused damage to one of the two boats cited. In any event, it was, as he said, “a most successful night.”

On her maiden escort with the Group,
Duncan
had detected and attacked four separate U-boat advances in the space of one hour and fifty minutes, and in weather conditions where the ship was pitching and rolling wildly, and seas washing down the quarter deck made the work of loading and reloading the heavy D/Cs both difficult and dangerous.
³²
Gretton used the loud-hailer to praise the behavior of his ship’s company during their first baptism of fire. The two corvettes had also given a good account of themselves, although each committed an error: In dropping two D/Cs at 2208 to scare off any U-boats in her vicinity,
Sunflower
inadvertently dropped a calcium flare that lit up the entire seascape—“rather an unnecessary advertisement,” as her Canadian Captain, Lt.-Cmdr. J. Plomer, R.C.N.V.R., dryly put it.
Sunflower
turned back to extinguish the light and, on a second attempt, by going hard to starboard, drew it through the propeller stream.
³³
.

Snowflake
had a dicier experience, which Gretton called “an unusual slip in the drill.” During the sixth U-boat attack,
Snowflake
followed a radar contact at 0332 and sighted an approaching boat in the process of
diving. When about 200 yards astern of the boat’s swirl, the wheel was suddenly put hard-a-starboard, though no such order had been given. As a result, the U-boat passed on a reciprocal bearing 200 yards down the port side and no D/Cs were fired.
Snowflake’s
Captain, Lieutenant Harold G. Chesterman, R.N.R., dropped three D/Cs between the U-boat and the convoy as scare tactics. At 0336 he gained an asdic bearing at range 2,000 yards and turned to the attack. As he did so, at 0338, ship’s hydrophone first detected, then lookouts sighted, a torpedo pass 20 yards down the port side.
³⁴

This was the only torpedo seen the night of 28th/29th. It was launched by U
-532
(Korv. Kapt. Ottoheinrich Junker), but it was not the only eel in the water. Just three minutes before, by periscope, Junker had launched a four-torpedo
Fächerschuss
(fan shot) from his bow tubes at what he called “the third steamer” in a column, estimated by him at 5,000–6,000 GRT. All the eels missed. The depth of run was three meters, which should have been shallow enough to hit a ship even in ballast. Seven and a half minutes later, Junker would hear end-of-run detonations. Meanwhile, using the two stern tubes that a Type IXC/40 boat commanded, he got off a double launch against
Snowflake
(only one of which torpedoes was sighted), missing again, as already noted, and hearing end-of-run detonations seven minutes later.

Junker states in his KTB (war diary) that as he placed the escort in his crosshairs, he could see convoy steamers in the background. His six misses in that crowded seascape were perhaps ineptitude, or just bad luck. The fault could not have been inexperience: the thirty-eight-year-old native of Freiburg im Breisgau had commanded U-boats since 1936, though it bears mention that he did not have a single ship to his credit. With U
-532
having to reload all tubes, the initiative now passed to
Snowflake
, which Junker’s periscope displayed steaming toward him at high speed, only 1,200 meters distant. “Alarm!” his KTB records, as U
-532
opened flood valves and dived to greater depth—and just in time, as
Snowflake
dropped a ten-charge pattern over him at 0343. When the noise and turbulence subsided at 0345,
Snowflake
regained asdic contact. With the recorder marking well, Chesterman came round to port, and at 0351 fired a ten-charge pattern set to 100 and 225
feet. This second attack, Chesterman noted, “is considered to be accurate.” Then, with only “doubtful” asdic contact showing on the recorder, and concerned that he should husband his D/Cs remaining for battles to come, Chesterman shaped course to rejoin the convoy.

Deeper than 225 feet, U—532 was still alive, but wounded. Junker wrote in his KTB:

Junker records that he remained submerged, experiencing or hearing various series of D/Cs—five more ten-patterns—“additional series or single drops”—“new depth charge attacks”—“three more series”—as far as 0140 (2340 GMT on the 29th) on 30 April, when he surfaced, the last hours having been spent breathing through potash cartridges because of the 3 percent level of CO
₂
in the boat. Troubled by intolerable noises inside the boat, he set course back to base. The BdU gave
U-532
credit for “two hits” and duly noted the boat’s ordeal: “She was hunted for fifteen hours.” The problem with the fifteen-hour story is that the D/Cs heard by U
-532
after
Snowflake s
two drops were not meant for her but for the U-boat involved in the
McKeesport
event, described below. The sum of U—532's patrol was: no hits, six misses, and one badly bent boat forced back to base.
³⁵

The BdU did not learn of U-532's alleged hits until 2 May. At the time of the night battle it was dismayed that not a single
Treffer,
or hit,
had been scored. In rationalizing the failure, it argued first that the boat’s messages to Berlin were inaccurate. They overestimated the convoy’s speed—certainly that was the case with U-650's initial estimates—and the reports from
U-386
and U
—378
on the enemy’s position were too far distant from each other to make any sense. Second, atmospheric or magnetic interference apparently was preventing BdU’s operational orders from getting through, since no acknowledgments were coming back, and no messages of any kind were received from the boats during the period from 0300 GST on the 29th to 1200 on the 30th. Third, Force 6 winds, heavy seas, and limited visibility greatly hampered surface operations.
³⁶
For the first time in a long while, Admiral Dönitz’s command and control system had been frustrated and bootless on the night of the 28th/29th. But an enterprising individual commander, operating on his own initiative, could break the string.

In the early daylight of the 29th, fulfilling Gretton’s expectation that, unable to overcome B7's night tactics, the U-boats might try submerged attacks in daytime,
U—258
(Kptlt. Wilhelm von Mässenhausen) slipped inside and under the convoy formation, where he took a position at periscope depth starboard of the convoy’s No. 4 column. In doing so, he somehow avoided the asdic sweeps by the escorts on day stations as well as by
Tay,
which was searching astern for damaged or shadowing boats, and by
Vidette,
which returned to her station at 0725 after searching out 15 miles. It was broad daylight. At exactly 0729 1/2, the furtive U—
258
scored a hit on the 6,198-GRT American Moore-McCormack freighter
McKeesport,
ship No. 42, the second ship in No. 4 column, which was on a return voyage from having delivered to Manchester, England, a cargo of grain, steel tanks, foodstuffs, and chemicals.
³⁷

Gretton was asleep in his sea cabin when the alarm bell rang. Dashing to the bridge, he ordered “Artichoke” at 0730. In this operation the ship in position “S,” astern, closes the torpedoed ship at maximum asdic speed, and ships in the “forward line,” that is, “A,” ahead, “B,” starboard bow, and “L,” port bow, turn immediately outward to a course reciprocal to the course of the convoy and sweep in line abreast at 15 knots or at the maximum asdic sweeping speed of the slowest ship, the wing ships passing just outside the convoy wake, the inner ship(s)
between the columns of the convoy, until reaching a line 6,000 yards astern of the position the convoy was in when the ship was torpedoed. All other escorts continue on the course of the convoy.

Five minutes later, Gretton saw a torpedo, which had passed through several columns without a hit, explode at the end of its run on the convoy’s port quarter, indicating an attack from starboard, probably along 180 degrees. The rescue trawler
Northern Gem
acquired an asdic contact astern of
McKeesport
and made an attack with three D/Cs. There was no result. And an “Observant” carried out by
Duncan
proved fruitless. Admiringly, Gretton called
U—258’
s action “a bold effort,” and, what was more, the attacker got away—for now.
³⁸

On board
McKeesport
the torpedo’s explosion had come as a complete surprise. The Chief Officer, Junior Third Officer, and two seamen-lookouts on the bridge made no periscope sighting. Neither did the U.S. Naval Armed Guard who manned a four-inch gun on the afterdeck. Nor did the seaman-lookout on the fo’c's’le, although on the starboard side he did see a long, dark, round object leap across a trough of the choppy sea, which he thought was a fish. He correctly identified a second torpedo that ran astern, but it was too late to warn about the first. When the warhead detonated with an awesome bang, it not only shook the whole ship; it opened a hole at the collision bulkhead of No. 1 hold, which, like holds 2, 3, and 5, was filled with sand ballast; put the steering apparatus out of order; flooded the forepart up to tween decks; and twisted plates, beams, and hatches. Fire spread through wooden grain fittings, but the inrushing sea put it out.

McKeesport
lurched to port, causing the British
Baron Graham
on that side to consider evasive action. Incredibly, the listing merchantman maintained convoy speed in her station for fifty minutes, until, with her engine room flooding, she started to sink at 0815, and the Master ordered Abandon Ship. Life nets were thrown over the side and the boats were lowered. Unfortunately, the boats became entangled in the nets, and so did some of the men who used them to climb down to rafts. Several seamen fell into the water, one of whom would later die from exposure, the only fatality from
McKeesport’
s complement. Last to leave were the Master and the crew of the Naval Armed Guard, under
command of Ensign Irving H. Smith, U.S.N.R., who gallantly stood by their gun until ordered to leave. The rescue ship
Northern Gem
came alongside and picked up the survivors: forty-three seamen, one critically injured, and twenty-five naval crew.

While the Master had cast overside his Confidential Books, including his codes, in a weighted container, he had neglected to jettison his ship’s log and charts, on which future rendezvous positions were marked. Accordingly,
Northern Gem
made an effort to sink
McKeesport
with her ship’s gun, but the derelict ship remained afloat. It was U.S. Navy Department policy, stated by Secretary of the Navy Frank Knox on 30 March 1942, that “no U.S. Flag merchant ship be permitted to fall into the hands of the enemy.” Since that was the policy and
McKeesport
could be boarded by a U-boat crew, Gretton ordered
Tay
to go back and hole the wreck, which she did with depth charges.