A Prize of Arms is a 1962 British crime film directed by Cliff Owen and starring Stanley Baker, Helmut Schmid, Patrick Magee and Tom Bell.
The troops are about to be dispatched to take part in a war in the Middle East and there is believed to be a large amount of pay on the premises, to be shipped out with them.
For the rest of the day they try to integrate themselves into the workings of the base, including being vaccinated for Overseas service, to avoid attracting attention.
As night falls, they change into military police uniforms and head for the pay headquarters again, announcing on arrival that they have had reports of a fire.
After the truck leaves the convoy, it is tracked down by the army, with the criminals seemingly cornered in a disused country barn.