The Triennial Bill providing for the summoning of Parliament at least once in three years, if necessary, in spite of the Crown, put a final end to the system of Personal Rule over which Charles had so far presided. … He accepted this on the same day as the Bill of Strafford’s Attainder. … The principles of the Petition of Right about personal liberty, particularly freedom from arbitrary arrest, were now finally established.

Winston Churchill, A History of the English-Sp…, loc. 1034