From the Valley.
Staunton, May 18.
--Gen. Breckinridge's victory at New Market was even greater and more complete than at first announced.
He captured six pieces of artillery and nearly one thousand stand of arms.
The loss of the enemy in killed, wounded, and prisoners is heavy.
Sigel run thirty miles without stopping, abandoning his hospitals and destroying a portion of his train.
His large cavalry force alone prevented us from burning the bridge in his rear before the rout and thereby capturing the whole.
Our success was chiefly due to a day and night march of over thirty miles, and commencing the attack before the arrival of one of his divisions, which was whipped when it did arrive.
Sigel commanded in person.
Brig. Gen. Stahi commanded his cavalry, while Gens. Sullivan and Couch commanded each a division.
The enemy encamped last night on Cedar Creek, the swollen condition of which alone checked their flight.
Our advance is two miles below Strasburg, and it is thought Sigel will continue to Martinsburg. 