On 22 May 1916, it was discovered that "Seydlitz" was still not watertight after repairs and would not now be ready until the 29th. The ambush submarines were now on station and experiencing difficulties of their own: visibility near the coast was frequently poor due to fog, and sea conditions were either so calm the slightest ripple, as from the periscope, could give away their position, or so rough as to make it very hard to keep the vessel at a steady depth. The British had become aware of unusual submarine activity, and had begun counter patrols that forced the submarines out of position. "UB-27" passed Bell Rock on the night of 23 May on its way into the Firth of Forth as planned, but was halted by engine trouble. After repairs it continued to approach, following behind merchant vessels, and reached Largo Bay on 25 May. There the boat became entangled in nets that fouled one of the propellers, forcing it to abandon the operation and return home. "U-74" was detected by four armed trawlers on 27 May and sunk south-east of Peterhead. "U-75" laid its mines off the Orkney Islands, which, although they played no part in the battle, were responsible later for sinking the cruiser carrying Lord Kitchener (head of the army) on a mission to Russia on 5 June. "U-72" was forced to abandon its mission without laying any mines when an oil leak meant it was leaving a visible surface trail astern.