Complex sentence: The remainder of the army, under General Thomas, retreated in good order to fight and win a very strategic battle at Chattanooga, Tennessee, which is 10 miles north of Chickamauga, Georgia, two month later.
Split into simpler sentences: The remainder of the army, under General Thomas, retreated in good order. This army went on to fight and win a very strategic battle at Chattanooga, Tennessee, which is 10 miles north of Chickamauga, Georgia, two month later.