The plot was, however, discovered.

Several members of Parliament were arrested, and two executed by orders of the Parliament.
Early in June Colonel Furness and his troop were called into Oxford, as it was considered probable that some expeditions would be undertaken, and on the 17th of that month Prince Rupert formed up his horse and sallied out against the outlying pickets and small troops of the Parliament.

Several of these he surprised and cut up, and on the morning of the 19th reached Chalgrove Field, near Thame.

Hampden was in command of a detachment of Parliamentary troops in this neighborhood, and sending word to Essex, who lay near, to come up to his assistance, attacked Prince Rupert's force.

His men, however, could not stand against the charge of the Royalists.