Complex sentence: The Republicans denounced the peace-oriented Democrats as disloyal Copperheads and won enough War Democrats to maintain their majority in 1862; in 1864, they formed a coalition with many War Democrats as the National Union Party which reelected Lincoln easily.
Split into simpler sentences: The Republicans denounced the peace-oriented Democrats as disloyal Copperheads and won enough War Democrats to maintain their majority in 1862. In 1864, they formed a coalition with many War Democrats as the National Union Party which reelected Lincoln easily.