Complex sentence: Shortly before first light, Keyes' men moved to a wadi, where they sheltered until dark on the second night, then moved off but their Arab guide refused to accompany the party in the deteriorating weather.
Split into simpler sentences: Shortly before first light, Keyes' men moved to a wadi, where they sheltered until dark on the second night then moved off. Their Arab guide refused to accompany the party in the deteriorating weather.