Renumbering of the Territorial Force in 1917

Men serving in the Territorial Force got new numbers in 1917 and a great deal can be determined about their service from these numbers. This page should help you understand what it all means.


Many people know that “in early 1917 all TF soldiers were allocated new 6 digit numbers”. As with anything involving the administration of an organisation as complex and idiosyncratic as the British Army, it isn’t quite that simple. These pages, kindly provided for the Long, Long Trail by Jock Bruce, are an attempt to explain the system.

Background: TF numbering before 1917

Numerous different numbering systems

Up to the end of 1916 men in each TF unit (infantry battalion, artillery brigade, field ambulance, etc) were numbered using a system unique to that unit – often by allocating the number 1 to the first man to join the unit on its formation in 1908 and continuing from there. In some cases the system was a continuation or variation of that used by the Volunteer unit on which the new TF one was based. In other words there could be a Private 1234 in the 4th Battalion of the Umpshires and another in the 5th Battalion, as well as all the Privates 1234 in other TF units in other regiments.

What happened when a man changed units

When a man moved between TF units, even between battalions of the same regiment, he was renumbered. This was adequate for peacetime but not for the different circumstances of war. Renumbering resulted in inevitable errors and confusion, and an administrative burden. This became worse as the number of transfers between TF units (and between TF and non-TF units) increased after changes in regulations allowed the compulsory transfer of TF men to units other than the one in which they had enlisted.

Changes are made

In late 1916 and early 1917 a new numbering system was promulgated in five Army Council Instructions (ACIs), each one covering a different arm of service and each with a date of implementation some weeks or months in the future. There were several further ACIs intended to clarify and refine the instructions for renumbering. The pages dealing with individual arms include all these amendments up to December 1918. The ACIs differed in detail but followed the same general pattern. They defined who was to be considered a regular or TF soldier for the purposes of renumbering, allocated blocks of numbers to TF units for renumbering their soldiers and set out the rules for future numbering changes.


To understand the new system it is necessary to understand some of the terminology used. The following are simplified definitions –

  • “Corps” were effectively the different parts of the army as defined in the “Corps Warrant”. Pre-war a man enlisted in a particular corps and could not be compulsorily transferred to another. The RE and RAMC were single corps; the RA consisted of two corps, (the Royal Horse & Field Artillery and the Royal Garrison Artillery); ‘corps of cavalry’ and ‘corps of infantry’ were more complex.
  • “Transferred” meant a man was permanently moved to another corps.
  • “Posted” meant a man permanently moved to another unit of the same corps.
  • “Attached” meant exactly that – the man was temporarily attached to another unit or corps for a particular purpose, but he remained part of his original unit and corps for pay and promotion e.g. the RAMC men attached to infantry battalions.

The basics of the 1917 numbering system

The definition of who was a TF man and who was a regular for the purposes of the initial renumbering was standard for all arms. It was based purely on the type of unit in which a man happened to be serving at the time, rather than what form of attestation he had signed at enlistment and it did not alter the terms and conditions under which he served. Confusingly, subsequent changes of a man’s number could be determined by his type of attestation.

TF soldiers were defined as (1) all soldiers serving in TF units at the time of renumbering who had either

  • Enlisted direct into such units or
  • Had been posted directly to such units from Army Reserve Class B or
  • Had been transferred or posted to such a unit from any other corps or unit.

And (2) all soldiers belonging to TF units who were temporarily attached to other units or corps.

All other soldiers were considered as regulars are were not affected by the renumbering.

What happened in the 1917 renumbering?

By the date specified for his particular arm of service, every TF soldier was renumbered, receiving a six-digit number (five-digit in the case of some Yeomanry units) from the block of numbers allocated to his unit. The block of numbers allocated to a unit was used for all parts of the unit – 1st, 2nd and 3rd lines, the depot, men on TF Reserve, men temporarily disembodied and men temporarily attached to other units and corps. The distribution of numbers to the different elements of a unit followed no set pattern.

A TF soldier now retained this number as long as he continued to serve in a particular corps, even if he was posted to another TF or regular unit in that corps. He would only be renumbered if he transferred to another corps.

The details

The ACIs are sometimes contradictory, are susceptible to different interpretations and there were doubtless many errors made by the clerks responsible for actually executing the changes.

Researchers should be cautious about drawing too many conclusions about an individual based solely on the TF number allocated to him – a close reading of the rules will show that a man could be allocated a TF number without serving in the unit concerned.

The blocks of numbers allocated to each TF unit can be seen by clicking our links below:

Renumbering the TF Yeomanry

Renumbering of TF Royal Artillery

Renumbering the TF infantry

Renumbering the TF Royal Engineers

Renumbering the TF Royal Army Medical Corps


A soldier’s life

The Territorial Force

New British Army numbers issued in 1920