The order of a Benedictine reform movement, the Bursfeld Congregation, joined in 1465 - supervisory law passed from Siegburg to Gross St. Martin. The subsequent reconstruction while retaining large parts of the previous building took place until the church was re-consecrated in 1481. In 1583 during the Cologne War the monastery was again looted. The arrival of Dutch soldiers caused the nuns to flee to Cologne in 1620, and in 1632 they escaped the troops from Sweden. At the end of the Thirty Years' War, the monastery was in financial emergency, also due to the permanent high expenses for the fortification of the island (strong floods 1651/1658).