The siege of Metz (October 1552-January 1553) was a failed Imperial attempt to recapture Metz that was one of Charles V's last major military operations and that was said to have played a part in the decline of his health and his decision to abdicate (Fifth Hapsburg-Valois War).
In 1551 Henry II of France entered into negotiations with the German Protestant Princes, led by Maurice of Saxony. The Princes wanted an ally against Charles V, and in return for French help were willing to offer Henry the 'three bishoprics' of Metz, Toul and Verdun, then part of the Duchy of Lorraine (then part of the Holy Roman Empire).
The French invaded Lorraine in March 1552 and in April they captured Metz and Toul. Metz was taken with the help the bishop of Metz. The French army was commanded by Francis, duke of Guise, who would also later lead the defence of the city. The French also attempted to take Strasburg, but were repulsed. Henry II reached the Rhine, but then turned back west, taking Verdun in June, before returning home.
At the same Maurice of Saxony and the German Protestant leaders moved towards Innsbruck, in an attempt to capture the Emperor Charles V. Charles only just managed to elude capture and was unable to intervene in Lorraine during the summer of 1552. In May he left southern Germany and made a daring but failed attempt to reach the Netherlands, where he could raise troops. He then managed to escape east from Innsbruck, and Maurice didn’t dare follow him. Peace negotiations soon followed, and by the late summer Charles and most of the Protestant leaders had come to terms. Charles had already raised a sizable army, which he now led to Augsburg, then on to Ulm and Strasburg. Charles was also able to add a large number of Protestant troops to his army.
Charles now decided to attack Metz. The city was strongly held. Guise had been given plenty of time to improve the fortifications. Most of the population had been sent away, buildings outside the walls had been demolished and provisions gathered. The garrison was 10,000 strong and there was a field army in the area. Guise also had the help of Camillo Marini and the French engineer Saint-Rémy. Guise was a successful commander with an impressive ability to motivate his men, and he would use that skill to great effect at Metz.
Charles had around 45,000 men, and he was supported by the Duke of Alba (then a successful military commander, rather than the infamous ruler of the Netherlands he is now remembered as). Charles was later joined by Albert Alcibiades, margrave of Brandenburg-Kulmbach, a notorious rebel against his authority who was won over by Alba bringing reinforcements with him, but losing Charles much support in Germany.
Alba was first to reach Metz, arriving outside the city with the advance guard on around 19 October. Charles V had been sidelined by an attack of gout, and didn't join the army until 20 November, but the siege proper began on 31 October. The arrival of Alcibiades allowed the Imperial forces to complete a blockade of the city, but the Imperial army was a multi-national force, split by intense rivalries. The Netherlands contingent hated the Spanish, and their leaders criticised Alba's approach to the siege. There were also German, Bohemian and Italian contingents, each with their own rivalries.
Eventually the bombardment had its impact. On 28 November the curtain wall between the old towers of Massieux and Ligniers began to lean outwards, and then at 2pm the wall collapsed outwards over a long stretch of the wall. This should have led to an assault, but Guise had prepared for this possibility by building an interior ditch and rampart (as first used during the defence of Pisa in 1500), and Charles couldn't get his men to attempt an attack. According to Alba after this failure Charles was so angry that it triggered his decision to enter a monastery. Only a few years later, after abdicating from his titles, he did just that.
During December Charles continued to press the siege. There was a limited attempt at mining the walls, and massive gun batteries were built, but the siege had been started too late in the year. The winter weather now struck, making work in the trenches very difficult. Scurvy, dysentery and typhus also hit the Imperial forces.
By the end of 1552 it was clear that the siege had failed. Charles pressed on with it for rather longer than was sensible, and as a result his army suffered very heavy losses, halving in size (this includes a large number of deserters).
The siege was lifted on 1 January 1553 when Charles left. A few days later Albert Alcibiades and the rearguard retired after covering the retreat. The retreat was well organised, but that couldn't disguise the total failure of this major military effort.
The failure of the siege had a great impact on Charles. His health had improved during the siege, but it collapsed after its failure. He did make another attempt to retake the bishoprics in 1554, but this also ended in failure (including a minor defeat at Renty, 12 August 1554, his last battle, during an invasion of Picardy). The bishoprics were retained by France at the end of the Fifth Hapsburg-Valois War, and officially ceded to France at the end of the Thirty Years War.