A Spanish-Austrian army defeats a French army at the Battle of Pavia.

The Battle of Pavia, fought on the morning of 24 February 1525, was the decisive engagement of the Italian War of 15211526 between the Kingdom of France and the Habsburg empire of Charles V, Holy Roman Emperor as well as ruler of Spain, Austria, the Low Countries, and the Two Sicilies.

The French army was led by King Francis I of France, who laid siege to the city of Pavia (then part of the Duchy of Milan within the Holy Roman Empire) in October 1524 with 26,200 troops. The French infantry consisted of 6,000 French soldiers and 17,000 foreigners: 8,000 Swiss mercenaries and 9,000 German-Italian black bands. The French cavalry consisted of 2,000 gendarmes and 1,200 lances fournies. Charles V, intending to break the siege, sent a relief force of 22,300 troops under the command of the Fleming Charles de Lannoy, Imperial lieutenant and viceroy of Naples, and of the French renegade and captain-general Charles III, Duke of Bourbon. The Habsburg infantry consisted of 12,000 German Landsknechte, 5,000 Spaniards, and 3,000 Italians, and its command was exercised by an Italian Condottiero, the Marquis of Pescara, in conjunction with the German military leader Georg Frundsberg and the Spanish captain Antonio de Leyva who was in charge of an Imperial garrison inside Pavia. The cavalry, led by Lannoy and Bourbon, consisted of 1,500 knights and 800 lances.The battle was fought in the Visconti Park of Mirabello di Pavia, outside the city walls, where Pescara and Frundsberg stationed their forces in pike and shot formation. Francis took a personal initiative and led a cavalry charge against Lannoy, with the possible intent of capturing Bourbon, but it was held by German and Spanish pikemen and ravaged by arquebus fire. The arquebusiers formed a part of the Spanish colunellas and of the German doppelsldners. A mass of Spanish and German foot soldiers descended on the French cavalry from all sides and began systematically killing the French gendarmes. The remaining French forces, including Swiss mercenaries and Black bands, intervened to protect the King but were surrounded by the pikemen in front of them and by the garrison of Pavia that sortied from the town.

In the four-hour battle, the French army was split and defeated in detail. Many of the chief nobles of France were killed, and others including Francis I himself were captured. He was imprisoned in the nearby tower of Pizzighettone and later transferred to Spain, where Charles V was residing for his upcoming marriage with Isabella of Portugal. Together they signed the Treaty of Madrid of 1526, by which Francis abandoned claims over the Imperial Duchy of Milan and ceded Burgundy to the House of Habsburg in exchange for his freedom.

The outcome of the battle cemented Habsburg ascendancy in Italy and Europe, but Francis denounced the treaty after his liberation and soon re-opened hostilities over Burgundy and Milan.

The House of Habsburg (), alternatively spelled Hapsburg in English (German: Haus Habsburg, pronounced [haʊ̯s ˈhaːpsˌbʊʁk] (listen); Spanish: Casa de Habsburgo [aβzˈβuɾɣo]; Hungarian: Habsburg család), also known as the House of Austria (German: Haus Österreich, pronounced [haʊ̯s ˈøːstəʁaɪ̯ç] (listen); Spanish: Casa de Austria), is a German dynasty which was once one of the most prominent royal houses of Europe in the 2nd millennium.

The house takes its name from Habsburg Castle, a fortress built in the 1020s in present-day Switzerland by Radbot of Klettgau, who named his fortress Habsburg. His grandson Otto II was the first to take the fortress name as his own, adding "Count of Habsburg" to his title. In 1273, Count Radbot's seventh-generation descendant Rudolph of Habsburg was elected King of the Romans. Taking advantage of the extinction of the Babenbergs and of his victory over Ottokar II of Bohemia at the battle on the Marchfeld in 1278, he subsequently moved the family's power base to Vienna, where the Habsburgs ruled until 1918.

The throne of the Holy Roman Empire was continuously occupied by the Habsburgs from 1440 until their extinction in the male line in 1740 and, after the death of Francis I, from 1765 until its dissolution in 1806. The house also produced kings of Bohemia, Hungary, Croatia, Spain, Portugal and Galicia-Lodomeria, with their respective colonies; rulers of several principalities in the Low Countries and Italy; and in the 19th century, emperors of Austria and of Austria-Hungary as well as one emperor of Mexico. The family split several times into parallel branches, most consequentially in the mid-16th century between its Spanish and Austrian branches following the abdication of Charles V. Although they ruled distinct territories, the different branches nevertheless maintained close relations and frequently intermarried.

Members of the Habsburg family oversee the Austrian branch of the Order of the Golden Fleece and the Imperial and Royal Order of Saint George. The current head of the family is Karl von Habsburg.