Complex sentence: Elements of the 50th (Northumbrian) Infantry Division penetrated the line and established a bridgehead west of Zarat on 20/21 March but a determined counter-attack by 15th Panzer Division destroyed the pocket, re-establishing the line by 22 March.
Split into simpler sentences: Elements of the 50th (Northumbrian) Infantry Division penetrated the line and established a bridgehead west of Zarat on 20/21 March. A determined counter-attack by 15th Panzer Division destroyed the pocket, re-establishing the line by 22 March.