Oxford, the county town of Oxfordshire, is situated at the confluence of the Thames (Isis) and Cherwell, and on the borders of Berkshire. It is a "county borough" and seat of a Bishop and returns one member to Parliament, formerly two. Founded, probably, in the first quarter of the 10th century, it soon became important as a market and a place of pilgrimage. Its strategic importance was conspicuous in the struggle between Matilda and Stephen (1142), and in the Civil Wars when it was Charles I.'s headquarters and the seat of his Parliament. In the Middle Ages, too, Parliaments frequently met there. Latimer and Ridley were burnt there in 1555 and Cranmer in 1556.