With American lives under imminent threat, George Washington affirmed that the Commander-in-Chief cannot wage war without Congressional approval.
During President Washington's tenure, Americans on the Southwest Frontier regularly clashed with tribes native to that region as our young nation began the process of seizing the continent. During the summer of 1791, for example, the Creek Indians - more properly called the Muskogee - joined with several other tribes to attack American settlers on the Cumberland River. The following year, settlers were regularly violating federal promises to stay off land that by treaty belonged to Indians. Governor of the Southwest Territory William Blount, who likely favored war with the Creek and other tribes, reported over 100 white settlers killed or taken captive in 1792. As the year wore on, so did attacks on settlers, and they continued apace in 1793.
That summer, President George Washington received a letter from the Governor of South Carolina, William Moultrie, written at a time when Americans had been attacked and killed, and additional attacks seemed imminent. Would the Commander In Chief please send his fellow citizens some help?
Here is how President Washington responded (emphasis added):
Philadelphia, August 28, 1793.
Dear Sir: I have received your letter of the 11th of the last month.
Having conceived an opinion highly favorable to General Pickens, I invited him to repair to this city, in order that I might obtain from him such facts and information as would be essential to an offensive expedition against the refractory part of the Creek Nation, whenever Congress should decide that measure to be proper and necessary. The Constitution vests the power of declaring war with Congress; therefore no offensive expedition of importance can be undertaken until after they shall have deliberated upon the subject, and authorized such a measure.
So 218 years ago, the ratification of the Constitution having just occurred, the first president of the United States insisted in the face of raids on the homeland, and the virtual certainty of future attacks, that he couldn't commit to a military response without the permission of the United States Congress.