 In the early stages of mobilisation the men of the AIF were selected under some of the toughest criterion of any army in World War I and it is believed that roughly 30 per cent of men that applied were rejected on medical grounds.In order to enlist, men had to be aged between 18 and 35 years of age (although it is believed that men as old as 70 and as young as 14 managed to enlist), and they had to be at least five foot six inches tall (168 centimetres), with a chest measurement of at least 34 inches (86 centimetres).Many of these strict requirements were lifted later in the war, however, as the need for replacements grew.