These proceedings were soon followed by another application on the part of the Provincial Convention of Massachusetts, setting forth the difficulties under which they were laboring for want of a regular form of government; requesting explicit advice respecting the formation of a new government; and offering to submit to such a general plan as the Congress might direct for the colonies, or to endeavor to form such a government for themselves as should not only promote their own advantage, but the union and interest of the whole country.[29] Placed in this manner at the head of American affairs, the Continental Congress proceeded, at once, to put the country into a state of defence, and virtually assumed a control over the military operations of all the colonies. They appointed committees to prepare reports on military measures: first, to recommend what posts should be occupied in the city of New York; secondly, to devise ways and means for procuring ammunition and military stores; thirdly, to make an estimate of the moneys necessary to be raised; and fourthly, to prepare rules and regulations for the government of the army. They then proceeded to create a continental, or national army. To the battle of Lexington had succeeded the investment of Boston, by an army composed of regiments raised by the New England provinces, under the command of General Ward of Massachusetts. This army was adopted by the Congress; and, with other forces raised for the common defence, became known and designated as the American Continental Army.[30] Six companies of riflemen were ordered to be immediately raised in Pennsylvania, two in Maryland, and two in Virginia, and directed to join the army near Boston, and to be paid by the continent.[31] On the 15th of June, 1775, Colonel George Washington, one of the delegates in Congress from Virginia, was unanimously chosen to be commander-in-chief of the continental forces.[32] Having accepted the appointment, he received from the Congress a commission, together with a resolution by which they pledged their lives and fortunes to maintain, assist, and adhere to him in his great office, and a letter of instructions, in which they charged him to make it his special care, "that the liberties of America receive no detriment."[33] In the commission given to the general, the style of "the United Colonies" was for the first time adopted, and the defence of American Liberty was assumed as the great object of their union.[34] On the 21st of June, Washington left Philadelphia to take command of the army, and arrived at Cambridge in Massachusetts on the 2d of July. Four major-generals and eight brigadier-generals were also appointed by the Congress for the continental army; rules and regulations for its government were adopted and proclaimed, and the pay of the officers and privates was fixed.[35]