Complex sentence: XXX Corps would form the western arm of the pincer but instead of making for Mont Pinçon, the 7th Armoured Division would swing east across the Odon River to take Évrecy and the high ground near the town (Hill 112).
Split into simpler sentences: XXX Corps would form the western arm of the pincer. In an alteration to Operation Perch, instead of making for Mont Pinçon the 7th Armoured Division would swing east, crossing the Odon River to take Évrecy and the high ground near the town (Hill 112).