The event that led to the Sack of Lawrence was the shooting of Douglas County Sheriff Samuel Jones on April 23, 1856, while he was attempting to make an arrest in Lawrence. On May 11, federal Marshal J.B. Donaldson proclaimed that the rebellious citizenry of Lawrence had interfered with the execution of warrants against the "Free-State" legislature, which had been set up in opposition to the official proslavery territorial government. Building on this proclamation and a finding by a grand jury that Lawrence's Free State Hotel was actually built as a fort, Sheriff Jones collected a posse of 750 southerners to enter Lawrence, disarm the citizens, wreck the press, and destroy the Free State Hotel.
On May 21, 1856, forces led by Sheriff Jones gathered closer to the town. A large force was stationed on Mount Oread and cannon planted so as to cover and command the place. The house of Lawrence resident Charles Robinson was taken as headquarters for the Marshal and the officers of his army. On every road leading to the town and on the opposite side of the river, detachments of troops were posted to prevent escape from such justice as the marshal and sheriff were now prepared to mete out. The forces mustered two flags. The blood-red flag, on which was inscribed "Southern rights," floated side by side that day with the "stars and stripes."
The two printing offices were gutted, the presses destroyed, and the types thrown in the river. The planned work was finished by destroying the Free State Hotel. The first shot was fired from a cannon on the opposite side of Massachusetts Street by David Rice Atchison, but it failed to hit the building. About fifty shots were afterwards fired with little effect upon the solid walls. Next the posse attempted to blow it up. Several kegs of gunpowder were exploded within, with no appreciable damage to the walls. Its destruction was finally effected by an incendiary, and in the early evening it was a roofless, smoldering ruin. This work was followed by petty robberies all through the half-deserted town. As the men left, they burned Robinson's private dwelling on Mount Oread.