and Parma, causing the War of Parma in June 1551. The main combat of this phase was the Siege of Mirandola (1551), during which the Franco-Farnese defenders repulsed attacks by the Papal-Imperial-Spanish forces. The belligerents agreed to a two-year truce on 29 April 1552, ratified by Charles V on 10 May, which ended the War of Parma. Schmalkaldic War and Sienese siege Meanwhile, Henry II allied with German Protestant princes against Charles V with the Treaty of Chambord on 15 January 1552. An early offensive into Lorraine, in the Second Schmalkaldic War, was successful, with Henry capturing the Three Bishoprics of Metz, Toul, and Verdun and securing them by defeating the invading Habsburg army at the Battle of Renty (12 August 1554). In 1552, an anti-Spanish revolt in the Republic of Siena gave Henry another ally; on 17 July 1552, a Franco-Sienese army managed to expel the Spanish garrison. The Sienese welcomed a French garrison to defend the Republic against Spanish recapture attempts. A French army invaded Tuscany in 1553 in support of the Sienese Republic. In January 1554, the Spanish started besieging the city of Siena. The French troops were attacked by an Imperial‐Florentine army and defeated at the Battle of Marciano by Gian Giacomo Medici (2 August 1554). After an 18-month-long siege, Siena fell to Spanish forces on 15 April 1555. Although a run by exiled Sienese loyalists continued to exist until 3 April 1559, the territory of the Republic of Siena was fully annexed to the Duchy of Florence under Cosimo I de' Medici with the Treaty of Cateau-Cambrésis (3 April 1559), and eventually became part of the Grand Duchy of Tuscany (1569). Papal front and St. Quentin A treaty in Vaucelles was signed on 5 February 1556 between Charles V and Henry II of France. After Emperor Charles' abdication in 1556 split the Habsburg empire between Philip II of Spain and Ferdinand I, the focus of the war shifted to Flanders. However, the truce was broken shortly afterwards. Pope Paul IV was displeased and urged Henry II to join the Papal States in an invasion of Spanish Naples. On 1 September 1556, Philip II responded by pre-emptively invading the Papal States with 12,000 men under the Duke of Alba. French forces approaching from the north were defeated and forced to withdraw at the Siege of Civitella in August 1557. Philip, in conjunction with Emmanuel Philibert, Duke