In 1642 the tension between the English Parliament and King Charles, which had been building throughout his reign, escalated sharply after the King had attempted to arrest five Members of Parliament, whom he accused of treason. Having failed, Charles fled London with his family; many historians believe these events made civil war probable. In anticipation of a likely conflict, both sides began preparing for war and attempting to recruit the existing militia and new men into their armies. Parliament passed the Militia Ordinance in March 1642 without Royal assent, granting themselves control of the county militias. In response, Charles granted commissions of array to his commanders, a medieval device for levying soldiers which had not been used for almost a century until the King reintroduced it during the Bishops' Wars (1639–1640).