Final answer:
Henry IV, the beloved French king from the House of Bourbon, converted to Catholicism to secure the loyalty of the French people and issued the Edict of Nantes to grant liberty of conscience and worship to French Protestants, the Huguenots.
Step-by-step explanation:
The beloved French king from the House of Bourbon who was the long-time leader of the Huguenots was Henry IV. After the deaths of his rivals in the War of the Three Henries, Henry IV ascended to the throne in 1594 and decided to convert to Catholicism to secure the loyalty of the French people. He issued the Edict of Nantes in 1598, which granted French Protestants, known as Huguenots, the liberty of conscience and worship.