Complex sentence: Garfield sent a telegram to Secretary of War Edwin M. Stanton alerting Washington to the need for reinforcements to avoid annihilation, and Lincoln and Halleck delivered 20,000 troops by rail within nine days.
Split into simpler sentences: Garfield sent a telegram to Secretary of War Edwin M. Stanton alerting Washington to the need for reinforcements to avoid annihilation. As a result, Lincoln and Halleck delivered 20,000 troops by rail within nine days.