Complex sentence: Urquhart, p.64 The 1st and 3rd Battalions spent all day trying to force a way through to the bridge but by nightfall they had failed and both battalions were reduced to around 100 men.
Split into simpler sentences: Urquhart, p.64 The 1st and 3rd Battalion spent all day trying to force a way through to the bridge. But by nightfall, they had failed and both battalions were reduced to around 100 men.