Religious conflicts permeated Charles's reign. His failure to successfully aid Protestant forces during the Thirty Years' War, coupled with such actions as marrying a Catholic princess, generated deep mistrust concerning the king's dogma. Charles further allied himself with controversial religious figures, such as the ecclesiastic Richard Montagu, and William Laud, whom Charles appointed Archbishop of Canterbury. Many of Charles' subjects felt this brought the Church of England too close to the Catholic Church. Charles' later attempts to force religious reforms upon Scotland led to the Bishops' Wars, strengthened the position of the English and Scottish Parliaments and helped precipitate the king's downfall.
Charles' last years were marked by the English Civil War, in which he fought the forces of the English and Scottish Parliaments, which challenged the king's attempts to overrule and negate Parliamentary authority, whilst simultaneously using his position as head of the English Church to pursue religious policies which generated the antipathy of reformed groups such as the Puritans. Charles was defeated in the First Civil War (1642 � 45), after which Parliament expected him to accept its demands for a constitutional monarchy. He instead remained defiant by attempting to forge an alliance with Scotland and escaping to the Isle of Wight. This provoked the Second Civil War (1648 � 49) and a second defeat for Charles, who was subsequently captured, tried, convicted, and executed for high treason. The monarchy was then abolished and a republic called the Commonwealth of England, also referred to as the Cromwellian Interregnum, was declared. Charles' son, Charles II, though he became king at the death of his father, did not take up the reins of government until the restoration of the monarchy in 1660. In that same year, Charles I was canonised as Saint Charles Stuart and King Charles the Martyr by the Church of England and is venerated throughout the Anglican Communion.