 By nightfall , around sixteen thousand men had been landed , and the ANZACs had formed a beachhead , although with several undefended sections . It stretched along Bolton 's Ridge in the south , across 400 Plateau , to Monash Valley . After a short gap it resumed at Pope 's Hill , then at the top of Walker 's Ridge . It was not a large beachhead ; it was under two miles ( 3 @.@ 2 km ) in length , with a depth around 790 yards ( 720 m ) , and in places only a few yards separated the two sides . That evening Birdwood had been ashore to check on the situation , and , satisfied , returned to HMS Queen . Around 21 : 15 he was asked to return to the beachhead . There he met with his senior officers , who asked him to arrange an evacuation . Unwilling to make that decision on his own he signalled Hamilton ; 
