How to find your ancestor's military records with an army number search

Army numbers were introduced to uniquely identify soldiers in the British Army. Before 1920, regiments each kept their own numbering systems, meaning a Private in the Royal Fusiliers and a Private in the Highland Light Infantry could share the same number. During the First World War, as the Army expanded rapidly, this became increasingly confusing. 

In 1920, a new standardised numbering system was introduced. Blocks of numbers were allocated to different corps and units, creating a unified approach that continued through the Second World War and beyond. These numbers followed a soldier throughout their service, even if they transferred to another regiment, making it easier to trace service personnel over continents and decades.  

Army numbers are more than admin: they can reveal when a soldier enlisted, which corps they first joined, and how their career developed across some of the most significant periods in British military history. 

Is an army number the same as a soldier number? 

Yes - in British records, the terms army number, service number, and soldier number generally refer to the same thing. You may see slight variations in phrasing across documents, but all describe the unique identifier assigned to a soldier. 

How to find out your ancestor's army number through service records, military honours and more 

As you build your family tree and uncover key details about the lives of your military ancestors, you'll encounter important military records which have been digitised and made searchable online. It's a good idea to search for a person's name (including their date of birth and location, if known) across all military collections on a genealogy website like Findmypast.  

The following record sets are some of the most accessible. As you rifle through precious snippets of military service and sacrifice, you'll likely encounter: 

• British Army Service Records, many of which include a service number alongside rank, regiment, and postings 
• Medal Index Cards and Medal Rolls, which are essential for First World War research, as nearly all soldiers who served overseas were issued medals. Soldier numbers appear here 
• Pension Records. If your ancestor was wounded or discharged, pension and discharge papers can be invaluable for uncovering their army number 
• British Army Casualty Lists, which include records of soldiers who were wounded, missing, or killed in action, complete with soldier numbers 
• Prisoner of War records are particularly useful for finding a soldier's number if they were captured as a PoW during either World War 

If your ancestor served after 1920 and their full record is still held by the Ministry of Defence, having their Army number will help you request it and glean as much information as possible. Searching online military records is the best port of call, as you may find their number in medal rolls/military honours, enlistment registers or wartime lists.