The British Government anticipated an invasion of Greece by the Germans in 1941 and decided to send troops to support the Greeks, who were already engaged against the Italians in Albania. The 2nd New Zealand Division was one of a number of Allied units dispatched to Greece in early March. By late March, 21st Battalion had arrived in Athens where it was to carry out guard duty of vital installations around the city while the rest of the division proceeded to the north of the country to garrison the Aliakmon line. On 6 April, the day after Germany declared war on Greece, elements of the battalion guarding docks near Athens experienced a bombing raid which caused minor wounds to a couple of men. On 8 April, the battalion began moving to the front to rejoin 5th Infantry Brigade, which was now stationed at Olympus Pass. However, en route the battalion was diverted to the Platamon Tunnel, which was 15 miles from the town of Larisa. The defences here had been prepared by D Company, of 26th Battalion. Orders were to hold the position and should any part of it be lost, a counterattack was to be immediately made. The battalion, which arrived on 9 April, set to work further improving the defences, assisted for three days by the company from 26th Battalion until its departure.