My brother being one of them. He missed out on inclusion in the draft by one month and 3 days. FYI: inclusion in the draft was for every male over 18 on January 1st - then there was the lottery for who actually got picked to do national service. You could apply for exemption from inclusion on religious grounds, ill health such as blindness or missing a limb, family responsibilities (elderly parents yes, kids no), attendance at university (free at the time) and employment in essential services (police and doctors mostly but also some engineers). This had to be done before the lottery, so that in theory everyone called up for national service was available to 'fight'. If you applied for an exemption, but they hadn't processed your application when your number came up in the lottery, they usually did their best to put you in a non-combat role until the application was processed. So many exemptions were applied for that there were years long delays in processing.