Complex sentence: In the ensuing battle, 13 of the Pakistani tanks were destroyed or incapacitated by the Indian forces which lost four of its own tanks damaged or destroyed, but had been able to draw the battle into its second day.
Split into simpler sentences: In the ensuing battle, 13 of the Pakistani tanks were knocked out by the Indians. They had lost four of their own tanks damaged or destroyed, and had been able to draw the battle into its second day.