Complex sentence: Subsequently the 2/15th Battalion in support advanced through them closely followed by the 2/19th Battalion while the 14th Battalion, London Regiment (London Scottish) and the divisional pioneers 1/12th Battalion, The Loyal North Lancashire Regiment remained in reserve.
Split into simpler sentences: Subsequently the 2/15th Battalion in support advanced through them closely followed by the 2/19th Battalion. The 14th Battalion 14th Battalion, London Regiment (London Scottish) and the divisional pioneers 1/12th Battalion, The Loyal North Lancashire Regiment remained in reserve.