The siege of Metz was a battle fought during the Franco-Prussian War from August 19 to October 27, 1870 and ended in a decisive Allied German victory. The French Army of the Rhine under François Bazaine retreated into the Metz fortress after its defeat by the Germans at the Battle of Gravelotte on 18 August 1870. The fortress was promptly surrounded by German forces under Prince Friedrich Karl of Prussia. The French Army of Châlons was sent to relieve the Army of the Rhine but was itself encircled and annihilated by the German armies at the Battle of Sedan on 1–2 September. Unable to capture the fortress by bombardment or storm, the besieging Germans resorted to starving the French to submission. French attempts to break out ended in defeat at the battles of Noisseville on 31 August – 1 September and Bellevue on 7 October. French food supplies ran out on 20 October and François Achille Bazaine surrendered the fortress and the entire Army of the Rhine, some 193,000 men, into German hands on 27 October. The annihilation of the French Army of the Rhine freed Prince Friedrich Karl's armies for operations against French forces in the Loire river valley for the rest of the war. Metz was annexed into the German Empire after the signing of the Treaty of Frankfurt on 10 May 1871. Background After being held at the Battle of Gravelotte, Marshal Bazaine retreated into the defenses of Metz. There he was besieged by over 150,000 Prussian troops of the First and Second Armies on 19 August. Prelude Napoleon III and Marshal Patrice de MacMahon formed the new French Army of Châlons, to march on to Metz to rescue Bazaine. Napoleon III personally led the army with Marshal MacMahon in attendance. The Army of Châlons marched north-east towards the Belgian border to avoid the Prussians before striking south to link up with Bazaine. The Prussians, under the command of Field Marshal Count Helmuth von Moltke, took advantage of this maneuver to catch the French in an encirclement. He left the Prussian First and Second Armies besieging Metz, except three corps detached to form the Army of the Meuse under the Crown Prince of Saxony. With this army and the Prussian Third Army, Moltke marched northward and caught up with the French at Beaumont on 30 August. After a stiff fight in which they lost 5,000 men and