When my wife (a Canadian citizen) applied for a passport in 1992 she sent in a Dept of Natl Defence birth certificate which is a small card similar in size to a driver’s license with the chicken scratch signaure of a Major who issued it. In 2002 before coming down to the U.S. she again applied for a Canadian passport(they can’t be renewed and are only good for 5 years) she again submitted the D.N.D. birth certificate but had to submit her certificate of registration of birth abroad because Passport Canada would not accept the D.N.D. birth certificate. Qualifications for passports in the 60’s was even more lenient and minor children were named on their mother’s passport, not having one of their own.
It says something when today’s rules need to be more stringent than the rules in place at the height of the Cold War.