 To the north was Finland 's only ice @-@ free port in the Arctic , Petsamo . The Finns did not have the manpower to defend it fully as the main front was down the Karelian Isthmus . In the battle of Petsamo , the Soviet 104th division attacked the Finnish 104th Independent Cover Company . The Finns gave up Petsamo easily and concentrated on delaying actions . The area was treeless , windy , and relatively low , offering little defensible terrain . However , during the winter , the Finns in Lapland had the advantage of almost constant darkness and extreme temperatures . The Finns executed guerrilla attacks against Soviet supply lines and patrols . As a result , the Soviet movements were halted by the efforts of one @-@ fifth as many Finns . 
