In April 1878, the armored squadron was reactivated for the annual summer training cycle, under the command of "Konteradmiral" Carl Ferdinand Batsch. "Grosser Kurfürst" joined the unit, which included her sisters "Preussen" and "Friedrich der Grosse" and the large ironclad , after her commissioning on 6 May. A grounding by "Friedrich der Grosse" caused serious damage to her hull and prevented her from taking part in the upcoming training cruise. The three ships left Wilhelmshaven on the 29th. "König Wilhelm" and "Preussen" steamed in a line, with "Grosser Kurfürst" off to starboard. On the morning of the 31st, the three ships encountered a pair of sailing vessels off Folkestone. "Grosser Kurfürst" turned to port to avoid the boats while "König Wilhelm" sought to pass the two boats, but there was not enough distance between her and "Grosser Kurfürst". She therefore turned hard to port to avoid "Grosser Kurfürst", but not quickly enough, and "König Wilhelm" found herself pointed directly at "Grosser Kurfürst"; her ram bow tore a large hole in "Grosser Kurfürst"s side.