Grant had known nothing of Early's detachment from Lee's army until the news came to him that the Confederates were marching upon Washington in threatening force. As has been said before, it was Grant's conviction that Washington ought to be able to take care of itself so long as the main body of the Army of Northern Virginia was kept busy in his own front at Richmond and Petersburg. Nevertheless, as soon as news came to him that Early had defeated Hunter and driven him out of the valley, and that the Confederates were rapidly advancing upon Washington, Grant detached a strong force, and hurried it to the capital city. In the meanwhile the authorities at Washington seem to have been thrown into a panic as dangerous as it was senseless. They did, indeed, take certain measures of defense. They put arms in the hands of the clerks in the several departments, and sought with these to make some show of opposition to the approach of the Confederate veterans. This was manifestly useless. The time had long gone by when untrained clerks, however well armed, could be expected to stand for one moment against the battle-hardened veterans who had learned their trade under Lee or Grant in the desperate struggles in Virginia. It is not an exaggeration but simple truth to say that at that time a single regiment from either the Army of Northern Virginia or the Army of the Potomac could easily and almost without effort have swept away a hundred thousand untrained militiamen, however patriotic they may have been, and however they may have been inspired with personal courage. To send a mob of department clerks, however numerous, against such a force as that which Early commanded was like sending sheep to a contest with wolves. It meant the butchery of the poor fellows, without the smallest hope that their sacrifice of life could yield anything of advantage to the Federal cause or could delay the Confederate progress by more than a few minutes at the most. But Grant had promptly met the danger by hurrying two corps of his veterans to Washington city. Fortunately for the Federal cause, this force got there in time to interpose itself effectively between Early and the capital. After burning the city of Chambersburg Early was compelled to retire, which he did at once without loss, taking up a strong position in the Valley of Virginia, where his presence as a continual threat to Washington city was more effective than his coöperation with Lee at Petersburg could have been. Posted in the valley, Early's little force of 8,000 men served to occupy twice or thrice that number of Grant's troops in the defense of Washington, and in preparation for repelling an apprehended invasion of the country north of that city.