On August 26, 1794, President George Washington writes to Henry “Light Horse Harry” Lee, Virginia’s governor and a former general, regarding the Whiskey Rebellion, an insurrection that was the first great test of Washington’s authority as president of the United States. In the letter, Washington declared that he had no choice but to act to subdue the “insurgents,” fearing they would otherwise “shake the government to its foundation.”

The Whiskey Rebellion of August 1794 was the product of growing discontentment, which had been expressed as early as 1791, of grain farmers who resented a federal tax imposed on their distillery products. As growers threatened federal tax collectors with physical harm, Washington at first tried to prosecute the resistors in the court system. In 1794, however, 6,000 men angry at the tax gathered at a field near Pittsburgh and, with fake guillotines at the ready, challenged Washington and the federal government to disperse them.

In response, Washington issued a public proclamation on August 7, giving his former Revolutionary War aide-de-camp and current Secretary of the Treasury Alexander Hamilton the power to organize troops to put down the rebellion. In his letter to Lee on August 26, Washington noted that the general populace considered the insurrection with “universal indignation and abhorrence” and said that he otherwise would not have authorized such a heavy-handed response. Washington knew that the nation, having only recently violently overthrown the tyrannical English king, was in a delicate state and did not want to appear as an equally despotic president. He waited to see if the insurgents would back down; they did not.

According to biographer Joseph Ellis in His Excellency, George Washington, the aging president mounted his horse on September 30 to lead a force of 13,000–larger than any American army amassed in one place during the Revolution–to quell the uprising. (The act of mounting his war horse was brief and largely symbolic; Washington made most of the journey by carriage.) Lee joined Washington and the army on its march to Pennsylvania. This was the first and only time a sitting American president ever led troops into battle. Washington abandoned the procession early, however, leaving Alexander Hamilton, the true mastermind of the military response to the insurrection, in charge of the final approach to Pittsburgh.

The rioters dispersed in the presence of the federal troops and bloodshed was averted. In the aftermath, Washington reported to Congress that although he had agonized about the decision and intended to uphold the constitutional right to protest unfair tax laws, the insurrection had to be put down or the survival of the young democracy would have been in peril. Congress applauded his decision, but Washington’s former Secretary of State Thomas Jefferson, who was in temporary retirement at his Monticello estate, viewed Washington’s decision to call out troops against fellow citizens as a dire threat to republican ideals and an abuse of presidential power. The uprising highlighted a growing division in early American politics which, by the end of Washington’s second term, pitted rural, agricultural interests, led by future Presidents Jefferson and James Madison, against the pro-industrial urban interests, represented by Hamilton and John Adams, and gave rise to the two-party political system.