Dönitz's influence on military matters was also evident. Hitler acted on Dönitz's advice in September 1944 to block the Gulf of Finland after Finland abandoned the Axis powers. Operation Tanne Ost was a poorly executed disaster. Dönitz shared Hitler's senseless strategic judgement—with the Courland Pocket on the verge of collapse, and the air and army forces requesting a withdrawal, the two men were preoccupied in planning an attack on an isolated island in the far north. Hitler's willingness to listen to the naval commander was based on his high opinion of the navy's usefulness at this time. It reinforced isolated coastal garrisons along the Baltic and evacuated thousands of German soldiers and civilians in order that they might continue to participate in the war effort into the spring of 1945.