Difficulties, of course, arose in the event of bad weather, or when the slow speed of the ships prevented the passage of about 180 miles being made in approximately twenty-four hours, and by April, 1917, it was evident that further steps were necessary to meet these difficulties, which were again causing heavy losses.

Early in April, then, by direction from the Admiralty, a conference was held at Longhope on the subject.

Admiral Sir Frederick Brock, Commanding the Orkneys and Shetlands, presided, and representatives from the Admiralty and the Commands affected were present, and the adoption of a complete convoy system to include the whole trade between the East Coast and Norway was recommended.

This proposal was approved by the Admiralty and was put into force as soon as the necessary organization had matured.
Escorting vessels had with difficulty been provided, although in inadequate numbers.

The first convoys sailed towards the end of April, 1917.
The system may be described briefly as follows.