A pack horse used by British forces during World War I, Belgium, circa 1916.
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What role did animals play during World War One?

3 August 2014 Last updated at 07:53 BST

This year, 4th August marks 100 years since the start of World War One.

All this week Newsround has been bringing you stories from the frontline, the battlefields of Belgium and France.

A total of 65 million troops from around the world fought in the war.

But in his latest film Ricky's been finding out about some unusual recruits who did their bit for the war effort too.