In early life Scrope served in the Scottish campaign of 1333 and was knighted at Berwick, where he fought at the Battle of Halidon Hill. He served in Scotland again in 1335 and in 1340 took part in the sea Battle of Sluys at the start of the Hundred Years War. In 1342 he served in Brittany and was present at the sieges of Vannes and Morlaix. He was in Flanders in 1345 and in 1346 fought as a banneret both at the Battle of Crécy and the Battle of Nevilles Cross. In 1347 he was at the siege of Calais and in 1350 in the sea battle off Winchelsea.