Complex sentence: The Nigerian Army under Buhari then pursued the Chadian Army as afar as 50 km into Chadian territory the 21st Armoured Brigade carried out the blockade and the fighting.
Split into simpler sentences: The Nigerian Army under Buhari then pursued the Chadian Army as afar as 50 km into Chadian territory. The 21st Armoured Brigade carried out the blockade and the fighting.