Third Franco-Castilian War (Foedus Sacrum)

The Third Franco-Castilian War, also known as the Fifth War of the Holy Alliance, was a major conflict revolving around Western Europe in the 16th Century. It was the first War of the Holy Alliance that drew non-European powers into the equation, in the form of Morocco, following the Kingdom of France's diplomatic alliance with the Marinid dynasty against Iberia. It was also the first War of the Holy Alliance to not include other powers on the side of the Alliance.

The war lasted just under two years, considerably shorter than most of the other wars the Alliance was involved in. This was due in part to the growing power of the joint and ever-closer Crowns of Castile and Aragon, and the bolstered military sported by Austria following its acquisition of Hungarian land in the Likan War. Although the Alliance made much greater gains than they had before, occupying most of Occitania and even parts of Burgundy and the River Seine, the entrance of the Ottoman Empire into the war in April 1542 (supposedly to contain Iberian aggression; practically to prevent Castilo-Aragon from weakening France, allowing it to expand further into Africa and Italy) led to a swift status quo ante bellum peace treaty for continental Europe bar a few reparations agreements. Scotland, however, lost all land below the Firth of Forth to England.