Complex sentence: Maj. Gen. Ormsby M. Mitchel, commanding the Federal troops in middle Tennessee, planned to move south with his army and seize Huntsville, Alabama, before turning east in hopes of capturing Chattanooga, Tennessee.
Split into simpler sentences: Maj. Gen. Ormsby M. Mitchel commanded the Federal troops in middle Tennessee. He planned to move south with his army and seize Huntsville, Alabama, before turning east in hopes of capturing Chattanooga, Tennessee.