On May 2nd forces left for an aerial operation in the vicinity of the Horn Reef. The operation was covered by the Grand Fleet. One of its objects was, as before, to attract the attention of the enemy’s naval forces to the North Sea. Even if no enemy force were actually drawn out, it was expected that the presence of the Grand Fleet in southern waters would soon become known to the enemy from neutral sources, with the result that vessels of the High Sea Fleet, intended for operations in the Baltic, might be detained in, or brought back to, North Sea ports. From information obtained subsequently from reliable sources, it appeared that the operation produced the intended result. Between the afternoon of May 2nd and daylight on the 3rd the Fleet left its bases. The 1st Light Cruiser Squadron, with 16 destroyers convoying the sea-plane-carriers _Vindex_ and _Engadine_, proceeded to a position just north of the Horn Reef, arriving at dawn on May 4th; the objective of the sea-planes was the zeppelin sheds at Tondern. The mine-layer _Abdiel_ proceeded to lay mines on the night of the 3rd–4th to the southward of the Vyl Lightship on the expected track of enemy vessels _en route_ to the North Sea via the Horn Reef. The mine-layer _Princess Margaret_ was directed to lay mines on the same night across the expected route taken by enemy vessels if coming out along the route passing the West Frisian Islands. Both mine-fields were completed without any interference on the part of the enemy. Three submarines were sent to positions off the Horn Reef, three to positions off the Vyl light vessel, and three to positions off Terschelling, to arrive on the evening of the 3rd.[E] [E] Two of our submarines collided while submerged off the Horn Reef, one being slightly damaged.