Why were British troops sent to concord? What happened as the British retreated there?

British troops are sent to confiscate colonial weapons, they run into an untrained and angry militia. This ragtag army defeats 700 British soldiers and the surprise victory bolsters theirconfidence for the war ahead

In the town of Concord. He had also heard that John Hancock and Samuel Adams, two leaders of the Sons of Liberty, were in Lexington. General Gage sent 700 British soldiers to find the weapons and arrest the two Patriot leaders.