The Regimental Number, as well as the later Social Insurance Number and Service Number provided Canadian soldiers with a unique means of identification.

The Canadian Army assigned numbers to Other Ranks (only) up to and including the Second World War. Officers began to receive Regimental Numbers towards the end of the 1939-45 conflict, and after the war, Regimental Numbers were assigned to soldiers in both the Regular and Reserve forces until the adoption of the Social Insurance Number as an identifier. The SIN was replaced in the 1990s with Service Numbers once more.

Often, the last name of a soldier coupled with the last three digits of his number were used to identify him (for example, web gear and clothing issued to an individual would often be marked with the last name and "last three" - ie SMITH 607.)

Regimental Numbers

Other Ranks were assigned a Regimental Number based on the unit he joined.

In the First World War, a document entitled Canadian Expeditionary Force, Instructions Governing Organization and Administration outlined the following:

Regimental Series Numbers

1-A block of Regimental Series Numbers will be allotted to each Unit of the CEF shortly after authorization. Each NCO and man is given one of these numbers.

2-When a man has been given a regimental number, that number belongs to him for the full period of his service. A man on transfer from one unit to another does not change his regimental number.

3-A regimental series number once allotted must not again be used even should the man so numbered be discharged. In such cases the number remains dead.

In the Second World War, every unit was assigned blocks of numbers, prefixed by a letter indicating the Military District in Canada in which the unit was based. There were 11 military districts in Canada, numbered from 1 to 13 (with 8 and 9 left out), and Regimental Numbers thus were prefixed with the letters A, B, C, D, E, F, G, H, I, J, K, L or M. Officers were largely identified by name and rank only.

During the Korean War, with the issue of the new monel metal ID discs, numbers identified the Military District in which the soldier was recruited.

Social Insurance Numbers

At about the time of Unification, the military moved to using the Social Insurance Number in place of the Regimental Number, and this was done up unto the 1990s.

Personal Records Identifier (PRI) ("Service Number")

One commonly held belief is that the SIN (often redundantly called a "SIN Number") could potentially lead to discrimination based on geography, as the first digits of SIN often identified where the bearer of that number was living when the number was assigned. A new series of Service Numbers (officially called a PRI, or Personal Records Identifier, but commonly called Service Number or SN both officially and unofficially) were introduced, in nine character format, with the first character being a letter and the following characters being Arabic numerals. The numbers appeared in the format XXX XXX XXX on the ID disc but was usually written XXXXXXXXX in documentation.

Researching Numbers

Two references are in print detailing the unit blocks of numbers, for the First World War:

• Wigney, Edward H. Serial Numbers of the CEF (Self-published, 1996. ISBN 0968075002). (The book's title seems like a misnomer; the quote above regarding CEF instructions twice refers specifically to "Regimental Numbers". "Serial Number" refers to something else entirely in a Canadian context, though the US Army does use "serial numbers" as individual identifiers.)

and the period surrounding the Second World War:

• Law, Clive M. Regimental Numbers of the Canadian Army, 1936-1960 (Compiled & Edited by Clive Law, Service Publications, Ottawa, ISBN 1894581024).