Complex sentence: With the Orcs outnumbering Dáin's army, Thranduil and Bard's forces, along with Gandalf and Bilbo, join the battle as some of the Orcs, Ogres, and Trolls attack Dale.
Split into simpler sentences: With the Orcs outnumbering Dáin's army, Thranduil and Bard's forces, along with Gandalf and Bilbo, join the battle. A second front is opened when another force of Orcs, Ogres, and Trolls attack Dale.