Complex sentence: Sponsored by his influential Congressman Elihu B. Washburne, Grant was named by the governor, Richard Yates, to train volunteers; he proved efficient and energetic in the training camps but desired a field command.
Split into simpler sentences: Sponsored by his influential Congressman Elihu B. Washburne, Grant was named by the governor, Richard Yates, to train volunteers. He proved efficient and energetic in the training camps but desired a field command.