He would change his mind and in a landmark general order authorize their enlistment.

From 1776 by David McCulough. Page 36.

In response to concerns in Congress over how much of the army was in fact made up of old men and boys, as well as Negroes and Indians, General William Heath reported:

There are in the Massachusetts regiments some few lads and old men, and in several regiments, some Negroes. Such is also the case with the regiments from the other colonies. Rhode Island has a number of Negroes and Indians. The New Hampshire regiments have less of both.

General John Thomas, who commanded the Massachusetts troops at Roxbury, also responded:

The regiments at Roxbury, the privates, are equal to any I served with [in the] last war, very few old men, and in the ranks very few boys. Our fifers are many of them boys. We have some Negroes, but I look upon them in general equally serviceable with other men, for fatigue and in action; many of them have proved themselves brave.

Like most southerners, Washington did not want blacks in the army and would soon issue orders saying that neither “Negroes, boys unable to bear arms, nor old men” were to be enlisted. By year’s end, however, with new recruits urgently needed and numbers of free blacks wanting to serve, he would change his mind and in a landmark general order authorize their enlistment.