When the USS President Lincoln was attacked and sunk by the German submarine U-90, on 21 May 1918, Lt. Izac was captured and held as a prisoner on board the U-90 until the return of the submarine to Germany, when he was confined in the prison camp. During his stay on the U-90 he obtained information of the movements of German submarines which was so important that he determined to escape, with a view to making this information available to the U.S. and Allied Naval authorities. In attempting to carry out this plan, he jumped through the window of a rapidly moving train at the imminent risk of death, not only from the nature of the act itself but from the fire of the armed German soldiers who were guarding him. Having been recaptured and reconfined, Lt. Izac made a second and successful attempt to escape, breaking his way through barbed-wire fences and deliberately drawing the fire of the armed guards in the hope of permitting others to escape during the confusion. He made his way through the mountains of southwestern Germany, having only raw vegetables for food, and at the end, swam the River Rhine during the night in the immediate vicinity of German sentries.