Complex sentence: On his retreat he was mortally wounded and only later found barely alive on the battle field by his troops where he was then carried to his wife who helped to ten to him on the way back to General Grant's estate to the north.
Split into simpler sentences: On his retreat he was mortally wounded and only later found barely alive on the battlefield by his troops. They carried him to his wife, who helped tend to him on the way back to General Grant's estate to the north.