164, 178, 181, 182, 206, 207, 208, 254, 256, 259, 272, 329, 354 and 356. Blackhawk provided tender services for the larger ships operating as six divisions. Mine Division 1: , , , , , Mine Division 2: , , , , , , , Mine Division 3: , , , , , Mine Division 4: , , , , , Mine Division 5: , , , , Buoying Division: , Patapsco, Patuxent, , Common difficulties with the sweeping procedure involved mine cables becoming entangled in the kites attached to the sweeping wires. Sweeping gear was often lost if the mine detonated and cut the sweeping cables. Approximately one-third of the ships were damaged by exploding mines. Two men were killed in separate incidents while attempting to haul mines aboard to clear fouled sweeping kites. It had been assumed the Mk 6 mine hydrostatic safety devices would minimize the risks of this procedure, but sweeping gear losses increased after unreliability of these safety devices was recognized. Countermining sequences initiated by destruction of a swept mine causing detonation of an undetected mine closer to one of the minesweepers were another source of damage. Some of this countermining was attributed to acceleration of the antenna fuze relay armature or seawater leaking into damaged mines rather than sympathetic detonation of explosives. The minesweepers were sometimes able to continue sweeping, but the trawlers were less durable. Seven men drowned when the Richard Bulkeley was sunk by a mine detonation on 12 July. Strauss discontinued use of the trawlers for minesweeping, but retained six for transporting replacement sweeping gear to minesweepers when wires were destroyed by exploding mines. The remaining 13 trawlers were returned to the Admiralty. Most damaged ships were repaired, but SC-38 was declared a total loss. Three more men of the minesweeping force were killed in individual accidents involving sweeping gear before Strauss declared the barrage cleared on 30 September 1919. The minesweepers found only about 25 to 30 percent of the mines laid a year earlier; but it was assumed the others had either broken free, sunk to the bottom, or been destroyed by premature explosions. Strauss was recognized as a Knight Commander of St Michael and St George for his efforts; but doubts about effectiveness of the minesweeping effort persisted into the 21st century. Post-war consequences As 1919 drew to a close, the onset of winter forced the suspension of