Complex sentence: At 1:00pm, German pioneers detonated four mines near the Canadian forward trenches, before the Germans attacked with six battalions, five more battalions in support and an additional six in reserve.
Split into simpler sentences: At 1:00pm, German pioneers detonated a series of four mines near the Canadian forward trenches before the Germans attacked with six battalions. Five more battalions were in support and an additional six in reserve.