six o'clock
As he concluded , a star shell broke and lit up a vast expanse of gleaming mud . To the rolling and rumbling was now added a far-away sound of tramping feet and song . `` Here they come ! '' exclaimed Tremenheere ; `` back to billets ; they changed at six o'clock , but it 's heavy going -- mostly wading in slosh . '' The marching came nearer and nearer , also the sound of singing and mouth-organs . '' ` Michigan , ' '' said Shafto , `` is a favourite ; poor old ` Tipperary ' is down and out . '' Presently the force which had been relieved , muddy to the waist , but splendidly cheerful , splashed into the great courtyard .