Henry III of Navarre's succession to the throne in 1589 was followed by a four-year war of succession to establish his legitimacy, which was part of the French Wars of Religion (1562–1598). Henry IV inherited the throne after the assassination of Henry III, the last Valois king, who died without children. Henry was already King of Navarre, as the successor of his mother, Jeanne d'Albret, but he owed his succession to the throne of France to the line of his father, Antoine of Bourbon, an agnatic descendant of Louis IX. He was the first French king from the House of Bourbon.
Henry's succession in 1589 proved far from straightforward. He and King Henry III were moving to besiege Paris at the time of the latter's death. The city and large parts of France, mostly in the north, were in the hands of the Catholic League, an alliance of leading Catholic nobles and prelates who opposed the Protestant Henry of Navarre as heir to the throne. Instead, they recognized Henry's uncle, Charles of Bourbon, as the heir, and on Henry III's assassination, they declared Charles king. As a result, Henry IV was forced to fight a civil war to assert his position as king, followed by a war against Spain, who continued to question his legitimacy.
After the death of Charles of Bourbon, the Catholic League's failure to choose a replacement claimant to the throne, in combination with Henry IV's conversion to Catholicism, led to a general recognition of the king in France. Henry IV's successors ruled France until the French Revolution, then returned during subsequent Bourbon restorations, and they founded dynasties in Spain and the Kingdom of the Two Sicilies.
Bourbon claim to throne
Henry of Navarre was descended through his father from King Louis IX of France. Robert, Count of Clermont (d. 1317), the sixth and youngest son of Louis IX but the only son besides Philip III to produce a surviving line, had married Beatrix of Bourbon and assumed the title of sire de Bourbon. Bourbon was elevated into a duchy for Robert's son Louis, who became the first Duke of Bourbon.
At the death of Charles IV, Duke of Alençon in 1525, all cadet branches of the House of Valois had become extinct, with the only remaining Valois being the royal family itself. The chief of the Bourbons became the first prince of the blood, the closest to the succession to the throne should the immediate family of the king become extinct. At the death of Charles III, Duke of Bourbon in 1527, the Vendôme branch of the House of Bourbon became the senior line of the family. At that time, Charles de Bourbon was Duke of Vendôme. His son Antoine de Bourbon married the Queen of Navarre. Antoine's son, Prince Henry of Navarre, inherited this title on his death from an arquebus wound at the siege of Rouen in 1562.
The legitimacy of Henry of Navarre's claim to the throne was still questioned, however. In similar cases, the throne had earlier passed to successors with a much closer blood link to the throne. Louis XII had succeeded Charles VIII as his second cousin once removed in the male line. Francis I had succeeded Louis XII as his cousin five times removed in the male line. The successions were legally unproblematic because consanguinity was acknowledged in law to the tenth degree. Henry of Navarre, on the other hand, could claim only an agnatic relationship to Henry III in the twenty-second degree. When Henry had become the heir presumptive to the throne in 1584, on the death of Francis, Duke of Anjou, polemicist Jean Boucher had been among those who protested that such a distance in blood meant Henry's claim to the throne had effectively lapsed and that therefore the French States-General had the right to elect a new king.
When Henry was a boy, it seemed highly unlikely that he would ever inherit the throne of France since Henry II had produced four surviving sons. However, the prince of Navarre's pedigree gave him a special place of honour in the French nobility since all scions of the Bourbon line were acknowledged as the princes of the blood. As Head of the House of Bourbon, Henry was officially the First Prince of the Blood, the first nobleman of the kingdom.