Licinius left a strong garrison in Byzantium but ferried the greater part of his troops across the Bosphorus to the Asian shore.

To maintain his force in Byzantium, and to secure his line of communication between Asia Minor and the city, retaining control of the narrow waters separating Thrace from Bithynia and Mysia now became imperative for Licinius.

He also assembled a second military force, under his newly elevated co-emperor Martinian, at Lampsacus (Lapseki) on the Asian shore of the Hellespont.

The second clash was fought near Gallipoli; a storm blew up which, fortuitously for Crispus, wrecked many of the Licinian vessels on the shore.

[2] This naval victory allowed Constantine to move his army across to Asia Minor, using a fleet of light transports to avoid Martinian's forces.