In January 1920, the United Mine Workers of America launched a campaign to unionize southern West Virginia, including the Tug Fork coalfield. The local coal operators were determined to keep the UMW out. Miners who joined the union were fired, evicted from their company-owned houses, and replaced by nonunion workers. Many fought back with guns in what developed into the Battle of the Tug, or the Three Days Battle of May 1921. Violence usually involving gunfire from the mountains at working miners in the valley, erupted sporadically through much of 1920 and into the spring of 1921.

On May 12-14, 1921, bullets peppered down on about a dozen mining towns in the Matewan-Williamson area, and nonunion miners fired back. Deputy sheriffs, mine guards, the recently created West Virginia State Police, and Kentucky National Guardsmen joined the fray. Thousands of shots were fired from rifles, pistols, and even machine guns. Bullets clipped telephone wires and ripped through homes as families cowered in fear. Bridges and tipples were dynamited. Businesses and schools closed. Three persons were shot and killed.

The Battle of the Tug ended on May 15 when State Police arranged a truce, with the aid of a physician who crawled under fire through the Kentucky mountains to make contact with the insurgents. During the fighting, Governor Ephraim Franklin Morgan asked President Harding to send federal troops "to prevent wanton slaughter of innocent citizens." Although Morgan's request was denied, it set the stage for sending federal troops into West Virginia in September to quell the Miners' March on Mingo and Logan.