Military genealogy is addictive. One medal roll leads to a battalion diary. One service number leads to a whole new theatre of war. Before you know it, you’re deep in casualty lists at 1am.
But military research is not the same as civilian family history. The records are structured differently, the terminology is confusing, and one wrong assumption can send you completely off course.
Here are practical, hard-earned tips to help you research British Army ancestors properly — especially from the First and Second World Wars.
1. Start With the Service Number (Not the Medal)
The most powerful identifier in British Army research is the service number.
Names repeat. Even unusual names repeat.
Service numbers do not.
Once you have a number, you can often determine:
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Regiment
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Approximate enlistment period
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Sometimes even battalion
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Transfer likelihood
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Territorial vs Regular vs Service Battalion status
For WWI in particular, service numbers often reveal more than people realise — especially when you understand regimental number blocks and renumbering patterns.
If you don’t have the number yet, check:
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Medal Index Cards (WWI)
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Service records (if they survive)
2. Understand That “Regiment” Is Not the Same as “Battalion”
This is one of the biggest beginner mistakes.
Someone might say:
“He was in the Devonshire Regiment.”
That tells you the regiment — but not the battalion.
In WWI and WWII, each regiment contained multiple battalions, and those battalions served in completely different places.
For example, one battalion could be in:
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France
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Another in Gallipoli
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Another in India
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Another at home
Without the battalion, you’re guessing the war story.
Always try to identify the battalion before drawing conclusions about where someone served.
3. Don’t Assume Early Enlistment Means Early Casualty
A common misconception:
“Low service number = died early in the war.”
Not necessarily.
Many men enlisted in 1914 and survived the entire war.
Others enlisted in 1916 and were killed within weeks.
Service numbers can tell you when someone joined — not how long they served.
4. Learn the Difference Between Regular, Territorial, and Service Battalions (WWI)
In WWI, the British Army expanded massively.
You will commonly encounter:
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Regular Army – pre-war professionals
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Territorial Force (TF) – part-time soldiers
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Service Battalions – Kitchener’s New Army volunteers
Each group had different numbering patterns and mobilisation timelines.
For example:
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Territorial units were renumbered in 1917
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Service Battalions often show rapid number growth between 1914–1916
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Regulars may have very low numbers compared to wartime volunteers
If you don’t understand the category, you can misdate enlistment by years.
Final Advice: Think Structurally, Not Emotionally
It’s easy to project stories onto ancestors.
But military records are administrative systems. They follow patterns.
If you learn:
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How numbering worked
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How battalions were structured
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How transfers occurred
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How mobilisation evolved
You stop guessing — and start analysing.
And that’s when military genealogy becomes genuinely powerful.
Or discover more about tracing your British Army ancestor here
Author: Matthew Holden