Most ex servicemen are able to repeat a lengthy service number many years after retiring.

The service numbers are useful as they can specifically identify a man in the official records which is very useful given the likelihood of sharing the same christian name and surname with many other servicemen.

The need for service numbers sprang from the need to account for the men and money that was spent on their upkeep and their wages.

Normally each Regiment would keep their own records and new recruits would be allocated the next available number on depot rolls. This number would differentiate them from any men with the same name.

If they transferred to another Regiment then they were allocated a new number although they often kept their number if transferred to another Battalion within the same Regiment.

Changes to the numbering system over the years

From the formalisation of regiments in 1881men were allocated a 4 digit number that was transferable if they moved to another regiment.

By 1917 an army wide system, with 6 digit numbers, began where every individual was allocated a service number that would stay with them in all ranks and in any regiment.

Every regiment were allocated blocks of numbers which they used for their recruits. When these were used up a new block was made available for their use.

This lasted until 1922 when a new numbering system was introduced and that in turn was replaced in 1941 when the numbers available ran out and longer numbers were introduced.

Practical use in family history

One of the important features for family historians is that finding a soldiers service number can be checked against the block of numbers issued to Regiments which will in turn give dates when he joined up to the Regiment.

For instance recruit number 1374 joined the Essex Yeomanry on 8 October 1914 , recruit1590 joined on 9 November 1914 and recruit number 1777 joined on 9 January 1915.

So if your soldier in Essex Yeomanry is one of the 400 men with a number between 1374 and 1777 you can estimate his date of joining quite accurately.

There are of course exceptions but in instances of missing Service Records it can help to date enlistments.

Where to next?

Army service numbers in depot rolls (sometimes called description books) can be found in the records of the National Archives WO 67.

The best source of information is the brilliant Army Service Numbers Blogspot which provides a lot of free advice on numbers and on numbers within specific Regiments. Click here to visit the blog.