The Times has this interesting compendium on the first cuckoo calls of the year from its extensive archive. This extract is from an article from 1917 sent from the Western Front during the Battle of Arras (above picture).
I heard the cuckoo first on April 22, calling amid bare woodlands in the occasional gleams of thin winter sunshine. A single chiffchaff – plucky little thruster that he is! – was singing impatiently not far behind the battle-line as long ago as on Easter Day, even while our guns thundered the overture of the Battle of Arra. Complete diary here: Spring at the front: nature amid desolation