For whom do the British soldiers begin looking? What is their purpose? Who do they find?

The British soldiers are looking for the rebel leaders, but these people have already fled the city and gone to the country where they will be safe.  By arresting the rebel leaders, they feel they might be able to squelch the rebellion.  However, they find no one and they have no one to arrest.

They British soldiers are looking for the rebel leaders and the rebel printers. They arrest Edes of the Boston Gazette and Paul Revere's cousin