The Battle of May Island was in fact a series of disastrous events that took place as the 40 ships and submarines were travelling from Rosyth to Scapa Flow for exercises with the Grand Fleet. Very sadly there were five collisions occurred between eight vessels resulting in the loss of 104 submariners, two submarines (K4, K17) and severe damage to four others (K6, K7, K14, K22) and a Cruisers (HMS Fearless).
On January 31st 1918 at 1830 the vessels weighed anchor and the entire fleet steamed in a single line nearly 30 miles (48 km) long. At the head of the line were the two cruisers Courageous and Ithuriel followed by the rest of the 13th Submarine Flotilla. These were followed by the battlecruiser squadron, HMAS Australia, HMS New Zealand, Indomitable and Inflexible with their destroyers. After these came the 12th Submarine Flotilla and finally the battleships.
To avoid attracting German U-boats, particularly as one was suspected to be in the area, after dark each vessel showed only a dim stern light to the following vessel and they all maintained radio silence. As each group passed the Isle of May at the mouth of the firth, they altered course and increased speed to 20 knots.
As the 13th Submarine Flotilla passed the island, a pair of lights (possibly minesweeping naval trawlers) were seen approaching the line of submarines. The flotilla altered course sharply to port to avoid them but K14's helm jammed and she veered out of line. Both K14 and the boat behind her, K12 turned on their navigation lights and eventually K14s helm was freed and she tried to return to her position in the line. The next submarine in line, K22 had lost sight of the rest of the flotilla in the mist and veered off the line with the result that she hit K14. Both submarines stopped whilst the rest of the flotilla, unaware of what had happened continued out to sea. K22 radioed in code to the cruiser leading the flotilla to say that she could reach port but that K14 was crippled and sinking.
About fifteen minutes later, the 2nd Battlecruiser Squadron passed the island and the two submarines, but the battlecruiser Inflexible hit K22 causing further damage. The battlecruiser bent the first 30 feet (9.1 m) of K22's bows at right angles and wrecked the ballast and fuel tanks. She settled by the bow until only the fin showed.
Meanwhile, Leir, Captain of Ithuriel, had received and decoded the message about the first collision between the two submarines and turned back to help them. As the submarines behind her turned to follow her, the 2nd Battle Squadron passed through the line and it was only through emergency turns by both groups of vessels that further accidents were narrowly avoided.
As the 13th Flotilla reached the Isle of May, they encountered the outbound 12th Submarine Flotilla. The leader of the 12th Flotilla, Fearless loomed out of the mist and collided with K17 which sank within a few minutes, although most of her crew were able to jump overboard.
As the submarines following Fearless turned to avoid their now stationary flotilla leader, the battlecruiser Australia narrowly missed K12, which turned to get out of the way, putting her on a collision path with K6. K6 tried to avoid her but in doing so hit K4, nearly cutting the latter in half. The seriously damaged K4 sank with all her ships company, during which she was hit by K7
At this point the 5th Battle Squadron of three battleships and their destroyers passed through the area unaware of what had happened, some of the destroyers cutting down the survivors of K17 struggling in the water. Only nine of the 56 men originally in the submarine survived and one of these died of his injuries shortly afterwards. Within 75 minutes, the submarines K17 and K4 had sunk, and K6, K7, K14, K22 and Fearless had been damaged.
A memorial cairn was erected in January 2002 at Anstruther Harbour which overlooks May Island.