The four ships were commissioned into the I Battle Squadron.[23] They saw overseas service during the Boxer Rebellion in China in 1900–1901 under the command of Marshal Alfred von Waldersee.[24] Following the return from China, the Brandenburgs were taken into drydock for modernization, which lasted from 1901 to 1905 depending on the ship.[25] During the reconstruction the superstructure was cut down, a second conning tower was added, and the steam boilers were replaced with newer models.[26] Kurfürst Friedrich Wilhelm and Weissenburg were sold to the Ottoman Empire in 1910 and renamed Barbaros Hayreddin and Turgut Reis, respectively.