The siege of Thionville was the siege of the town of Thionville during the Italian War of 1551–59. It was held by the Spanish against a French force under Francis, Duke of Guise and others. It lasted from 17 April to 23 June 1558 and resulted in a French victory. Course Guise's capture of Calais allowed him to counter-attack the Spanish. Henry II of France decided to concentrate his forces against Thionville, then one of the strongest towns held by Charles V, Holy Roman Emperor and thought to be impregnable. It threatened the French town of Metz, which sent out twenty bands of infantry and artillery. They were joined by one company of gendarmes, one of light cavalry under the comte d'Espinay and other infantry and cavalry, mainly from Toul and Verdun. These all arrived before on 26 April 1587 to reinforce the seigneur de Vieilleville's troops, which had invested the town nine days earlier. The arrival was not marked with drums or fanfares in an attempt to keep it secret from the besieged forces. Vieilleville set up pontoon bridges and anchored buoys in the fords. He had also dug in twelve emperor-calibre (33 pound 4 ounce - 34 pound) cannon, six grand culverins (15 pound 2 ounce - 15 pound 4 ounce) and other field pieces. Other troops came to reinforce the besiegers from Brie, Champagne, Bassigny, the Duchy of Orléans and other places, along with six cornets of cavalry, one each from Henry of Brunswick-Dannenberg (second son of Ernest I, Duke of Brunswick-Lüneburg), the younger son of the duke of Zweibrucken, the bastard son of Christoph, Duke of Württemberg and the nephews of Johann von der Leyen (archbishop of Trier), Daniel Brendel von Homburg (archbishop of Mainz) and George, Duke of Symerch. On 17 April Vieilleville's first troops arrived outside the town walls and dug siegeworks at key points, cutting off the food supply to the city. On 26 April the German troops arrived, along with the other French reinforcements sent by Imbert de Bourdillon, allowing the town to be completely surrounded. Early in May Guise sent a message demanding that the seigneur de Vieilleville await his arrival with a further 400 men at arms, 500 light cavalry and 1,000 mounted arquebusiers - he and Piero Strozzi finally arrived at the town on 28 May. This meant that the French force now totalled around 12,000 men, though other