Complex sentence: Larger Matilda II tanks were seen among the Matildas, which advanced through the artillery and anti-tank fire unscathed, the shells bouncing off and the tanks destroyed the German anti-tank guns with return fire and by rolling over them, killing the crews.
Split into simpler sentences: Larger Matilda II tanks were amongst the Matilda Is, which advanced through the artillery and anti-tank fire unscathed. The German shells bounced off with the tanks destroying the German anti-tank guns with return fire and by rolling over them, killing the crews.