WASHINGTON, June 28.

The Pawnee arrived at the Navy Yard this morning, bringing intelligence from Mathias Point According to a statement of persons in the expedition, Capt. Ward, of the Freeborn, yesterday obtained from the Pawnee a reinforcement of about twenty men, and united with others from his own vessel, comprising between thirty and forty men in all. They started in several cutters for Mathias Point, taking with them about two hundred bags, which were filled with sand on the shore, and with which breastworks were soon erected.

Whilst on returning to the Freeborn to obtain cannon for the battery, a force of the Confederate troops variously estimated at from 1,200 to 1,500, suddenly emerged from thick woods, where they were concealed, and poured a volley of shot into the party, who made a hasty retreat. Several of the men jumped into the water, swimming to the Freeborn. Capt. Ward protected the men as far as possible, firing twelve or fifteen shots among the rebels, but the effect could not be ascertained.

A letter written on board the United States sloop-of-war Pawnee, recently dispatched on foreign service, records this touching incident:

“In passing down the Potomac river, and arriving opposite Mount Vernon, a beautiful and graceful tribute was paid to the sacred remains that lie entombed in that hallowed spot. All hands were called, officers in swords and epaulets, sailors in their neat uniform, the fine guard of the Pawnee drawn up, with belt and musket ; at a given signal the large American ensign fell at half-mast, the ship’s bell tolled out its muffled tones, the melancholy drums rolled their funeral salute, while the presented arms and uncovered heads of officers and men paid a sad tribute of respect to him who was “first in war, first in peace, and first in the hearts of his countrymen;” and so the Pawnee passed on silent and mourning, for he by whose grave she glided was the Father of his Country—a country scarcely a lifetime old ; yet the children of the second generation are ready to tear it to pieces, and with its ruins hide forever from the eye of men that grave and all the deeds which make it so famous in the world.