Conversation so far:
What did Spike Milligan write during the second world war?
During the Second World War, Milligan served as a signaller in the 56th Heavy Regiment Royal Artillery, D Battery (later 19 Battery), as Gunner Milligan, 954024.
How long was he there?
CANNOTANSWER.

Question: did he write while there?
Self-contained rewrite: did Milligan write while there?