In 1415 the Confederates conquered Aargau. Kirchleerau now belonged to the subject territory of the city of Bern, the so-called Bernese Aargau. From the 15th century on, the village was part of the Lordship of Rued, a judicial district within the Office of Lenzburg. The owners of the lordship exercised the lower jurisdiction and were the most important landowners. After various noble families from the surrounding area had been in possession of the manor, it was acquired in 1520 by the Lords of May, who originally came from Italy. Their residence was Rued Castle in the neighboring Rued Valley. In 1528 the Bernese introduced the Reformation.