The unexpected victory of Prussia over France (19 July 187010 May 1871) demonstrated the superiority of breech-loaded steel cannon over muzzle-loaded brass. Krupp artillery was a significant factor at the battles of Wissembourg and Gravelotte, and was used during the siege of Paris. Krupp's anti-balloon guns were the first anti-aircraft guns. Prussia fortified the major North German ports with batteries that could hit French ships from a distance of 4,000 yards, inhibiting invasion.