Complex sentence: The day was almost a replica of the previous one and the regiment were back at Shellal at 21:30, but instead of resting overnight they moved to El Mendur, arriving there at 06:00 on 19 April.
Split into simpler sentences: The day was almost a replica of the previous one and the regiment was back at Shellal at 21:30. Instead of resting overnight, they moved to El Mendur, arriving there at 06:00 on 19 April.