Washington was concerned with Howe's movements during the Saratoga campaign to the north, and he was also aware that Burgoyne was moving south toward Saratoga from Quebec. Washington took some risks to support Gates' army, sending reinforcements north with Generals Benedict Arnold, his most aggressive field commander, and Benjamin Lincoln. On October 7, 1777, Burgoyne tried to take Bemis Heights but was isolated from support by Howe. He was forced to retreat to Saratoga and ultimately surrendered after the Battles of Saratoga. As Washington suspected, Gates' victory emboldened his critics. Biographer John Alden maintains, "It was inevitable that the defeats of Washington's forces and the concurrent victory of the forces in upper New York should be compared." The admiration for Washington was waning, including little credit from John Adams. British commander Howe resigned in May 1778, left America forever, and was replaced by Sir Henry Clinton.