 On 6 April the German invasion of Greece and Yugoslavia began . In order to help defend Greece , a composite force of three divisions of Australian , British and New Zealand troops were to be deployed , and were grouped together under the title of ' W ' Force . However , by the time the invasion began only two of the three divisions had arrived , and the New Zealanders were consequently spread thin , holding a position to the north of Katerini , where they were tasked to defend the strategic Olympus Pass to the south . During this time , the 28th ( Māori ) Battalion was attached to the 5th Infantry Brigade , which was later grouped with other Australian and New Zealand units to form the Anzac Corps . Vastly outnumbered , within two days the situation for the Allies was not good as the Germans had broken through the defences along the Bulgarian border and the Yugoslav resistance had collapsed . As the situation worsened , orders came down from brigade headquarters that the passes would be held " to the last man and last round " . 
