British Gen. Burgoyne was trying to push through northern Hudson River valley. After the recent British victories at Hubbardton, Fort Ticonderoga, and St. Clair, Burgoyne's plan was to defeat the American forces in the area and then continue south to Albany and on to the Connecticut River Valley, dividing the American colonies in half.
However by late July, Burgoyne's progress towards Albany had slowed to a crawl and his army's supplies began to dwindle. Burgoyne sent forth from Fort Miller a detachment of about 800 troops under the command of the German Lt. Col. Friedrich Baum. Half of Baum's detachment was made up of German mercenaries, while the other half consisted of local Loyalists, Canadians, and Indians. Baum was ordered to raid the supply depot at Bennington, which was guarded by fewer than 400 colonial militia.
On August 13th, en route to Bennington, Baum learned of the arrival in the area of 1,500 New Hampshire militia under the command of Gen. John Stark. Baum ordered his forces to stop at the Walloomsac River, about 4 miles west of Bennington. After sending a request for reinforcements to Fort Miller, Baum took advantage of the terrain and deployed his forces on the high ground. In the pouring rain, Baum's men dug in and hoped that the weather would prevent the Americans from attacking before reinforcements arrived. Deployed a few miles away, Stark decided to reconnoiter Baum's positions and wait until the weather cleared.
On the afternoon of August 16th, the weather cleared and Stark ordered his men ready to attack. Stark is reported to have rallied his troops saying There are your enemies, the Red Coats and the Tories. They are ours or this night Molly Stark sleeps a widow. Upon hearing that the militia had melted away into the woods, Baum assumed that the Americans were retreating or redeploying. However, Stark had recognized that Baum's forces were spread thin and decided immediately to envelop them from two sides while simultaneously charging Baum's central redoubt head-on. Stark's plan succeeded, and after a brief battle on Baum's flanks, the Loyalists and Indians fled. This left Baum and his German dragoons trapped on the high ground without any horse. The Germans fount valiantly even after running low on powder. The dragoons led a saber charge and tried to break through the enveloping forces. However, after this final charge failed and Baum was mortally wounded, the Germans surrendered.
Shortly after this battle ended, while the New Hampshire militia was disarming the German troops, Baum's reinforcements arrived. The German reinforcements, under the command of Lt. Col. Heinrich von Breymann, saw the Americans in disarray and pressed their attack immediately. After hastily regrouping, Stark's forces tried to hold their ground against the German onslaught. Fortunately for the New Hampshire militia, before their lines collapsed a group of several hundred Vermont militiamen arrived to reinforce Stark's troops. The Green Mountain Boys, commanded by Seth Warner, had just been defeated at Hubbardton by British reinforcements and were eager to exact their revenge on the enemy. Together, the New Hampshire and Vermont militias repulsed and finally routed von Breymann's force.
Total British and German losses at Bennington were recorded at 200 dead, 700 captured, compared to 40 American dead, 30 wounded. Stark's decision to intercept and destroy the raiding party before they could reach Bennington was a crucial factor in Burgoyne's eventual surrender, because it deprived his army of supplies.
The American victory at Bennington also galvanized the rebels and was a catalyst for French involvement in the war.