 The New Zealand battalion withdrew , crossing the Pineios river ; by dusk , they had reached the western exit of the Pineios Gorge , suffering only light casualties . Macky was informed that it was " essential to deny the gorge to the enemy until 19 April even if it meant extinction " . He sank a crossing barge at the western end of the gorge once all his men were across and set up defences . The 21st Battalion was reinforced by the Australian 2 / 2nd Battalion and later by the 2 / 3rd . This force became known as " Allen force " after Brigadier " Tubby " Allen . The 2 / 5th and 2 / 11th battalions moved to the <unk> area south @-@ west of the gorge and were ordered to hold the western exit possibly for three or four days . 
