According to Robert Rhodes James' Gallipoli:
In about 6 hours a British Brigade was destroyed,with over 2,000 killed...the Turkish attack was an awesome spectacle.The astounded British suddenly beheld dim,dense masses of Turks pouring over the sky-line,not firing a shot,and advancing with the bayonet.The trenches on Chunuk Bair and at The Pinnacle were overwhelmed almost at once,and none of the British troops--over 1,000--survived....the Turks were cut down in swathes as they stormed down towards The Farm,but they moved so rapidly,and were visible so briefly,that the survivors reached the plateau in great numbers,exultant and fanatical..by 10 am,with the sun high in the sky,Baldwin and almost all his officers had been killed,and the remnants were falling back unto the shelter of the ravines,leaving over 1,000 officers and men dead or dying on the tiny plateau.Many of those who fled were lost in the ravines and never heard of again...
Seeking further details on the 23rd at Gallipoli August 1915.