Army claims war mends fences (5)

I believe the answer is:

swarm

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'army' is the definition.
(I've seen this before)

I cannot understand how the rest of the clue works.

(Other definitions for swarm that I've seen before include "Move in large numbers like locusts" , "Congregate" , "Mass of flying insects" , "Large number" , "Large group of flying insects" .)

I've seen this clue in The Independent.

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