Washington's strategic decisions in the summer of 1777 greatly assisted Gates' army at Saratoga at the cost of his own campaign in the Philadelphia vicinity because he thought Howe would travel northward to Saratoga and not southward to Philadelphia. He took a major risk in July by detaching over a thousand soldiers from his own army to travel north to join the Saratoga campaign. He sent aid north in the form of Major General Benedict Arnold, his most aggressive field commander, and Major General Benjamin Lincoln, a Massachusetts man noted for his influence with the New England militia and also one of Washington's most favorite generals. He ordered 750 men from Israel Putnam's forces defending the New York highlands to join Gates' army. He also sent some of the best forces from his own army: Colonel Daniel Morgan and the newly formed Provisional Rifle Corps, which comprised about 500 specially selected riflemen from Pennsylvania, Maryland, and Virginia, chosen for their sharpshooting ability. This unit came to be known as Morgan's Riflemen.