The Dade battle (often called the Dade massacre) was an 1835 military defeat for the United States Army. Under the Indian Removal Act of 1830 the U.S. was attempting to force the Seminoles to move away from their land in Florida provided by the Treaty of Moultrie Creek (following the American annexation of Spanish Florida see the Adams-Onis Treaty) and relocate to Indian Territory under the terms of the Treaty of Payne's Landing.

Two U.S. Army companies numbering 103 men under the command of Major Francis L. Dade were ambushed by approximately 180 Seminole and Black Seminole warriors as they marched from Fort Brooke on Tampa Bay to reinforce Fort King in Ocala. Only three U.S. soldiers and their guide Louis Pacheco survived the attack, and one died of his wounds the following day.

The battle sparked the Second Seminole War, which ended in 1842. By that time, most Seminoles had surrendered and been transported out of Florida, and a small group remained in central Florida (see Chipco's band) while another portion had moved further south to the edges of the Everglades in the Big Cypress (see Abiaka and Holatta Micco). There was no formal treaty ending this conflict which was another chapter in the long fought Seminole Wars.

On December 23, 1835, two U.S. companies of 110 men (including soldiers from the 2nd Artillery, 3rd Artillery and 4th Infantry Regiments) under Major Francis Langhorne Dade departed from Fort Brooke (present-day Tampa), heading up the Fort King military road on a resupply and reinforce mission to Fort King (present-day Ocala). Several Seminoles with their warriors assembled secretly at points along the march. Scouts reportedly watched the troops in their sky-blue uniforms at every foot of the route and sent reports back to the Indian chiefs.

The Seminoles in Florida had grown increasingly furious at attempts by the U.S. Army to forcefully relocate them to a reservation out west and Dade knew his men might be attacked by the Seminole Indians who were shadowing his regiment, but believed that if an attack were to occur, it would come during one of the river crossings or in the thicker woods to the south. Having passed these, he felt safe and recalled his flanking scouts in order that the command could move faster. Although the terrain he was now in, pines and palmettos, could not have concealed anyone who was riding horseback or marching, it could and did conceal crouched (or prone) warriors waiting in ambush.

The Seminoles refrained from attacking in the other places, not because they thought they could achieve better surprise later but because they were waiting for Osceola to join them. However, at the time he was busy trying to kill U.S. Indian Agent Wiley Thompson. They finally gave up waiting and attacked without him. The troops marched for five quiet days until December 28, when they were just south of the present-day city of Bushnell which is approximately 25 miles (40 km) south of Fort King. They were passing through a high hammock with oaks, pines, cabbage palms, and saw palmetto when a single shot rang out. The Seminoles had terrain and the element of surprise in their favor.

Many sources state that the first shot and the following storm of bullets brought down Major Dade and half his men. Dade, who was on horseback, was killed in the Seminoles' very first shot fired personally by Chief Micanopy, which by pre-arranged plan began the attack. Following Dade's death, command passed to Captain George W. Gardiner. Many of the soldiers, in two single file lines, were also quickly killed. Only a few managed to get their flintlock muskets from underneath their heavy winter coats. Gardiner, a graduate of the U.S. Military Academy, class of 1814, was also killed.

An eyewitness account by Seminole leader Halpatter Tustenuggee (also known as Chief Alligator) read as follows: