William the Conqueror didn't. He died well before William Marshall was born, before even William Marshall's father, John FitzGilbert was born.
William Ist, aka William the Conqueror (circa 1028 - 9 September 1087)
John FitzGilbert the Marshal, (c. 1105 - 1165)
Sir William Marshal, 1st Earl of Pembroke (1147 - 14 May 1219), also called William the Marshal (Guillaume le Maréchal)