Henry II, nicknamed Sangüesino because he was born at Sangüesa, was the King of Navarre from 1517, although his kingdom had been reduced to a small territory north of the Pyrenees by the Spanish conquest of 1512. Henry succeeded his mother, Queen Catherine, upon her death. His father was her husband and co-ruler, King John III, who died in 1516.
In 1525, Henry was taken prisoner at the Battle of Pavia, but he contrived to escape under a guise and in 1526, married Margaret, sister of King Francis I of France and widow of Charles, Duke of Alençon. By her, he was the father of Joan III of Navarre, and was consequently the grandfather of Henry IV of France. In 1530, after the Treaty of Cambrai between Castile and France, Charles V evacuated the northernmost county (merindad) of Navarre, Lower Navarre, allowing Henry to seize it. The Pyrenean border between Lower and Upper Navarre now constitutes the Franco-Spanish border in this sector.