Charles de Batz de Castlemore, was the son of Bertrand de Batz who was the son of a newly ennobled merchant and held the title of Seigneur de Castlemore et de la Plagne. His mother Francoise de Montesquiou D'Artagnan, came from very old noble family from Gascony. Charles was born between 1611 and 1615 at the Chateau de Castlemore, county of Fezensac near Lupiac.

His parents married in 1608 and Charles was not their only child. He had three brothers and three sisters, Charles being the youngest of them all. After a childhood in Gascony, of which not much is known, it seems Charles developed the desire to serve as a soldier..or rather as a Musketeer. He left his home and headed for Paris to join his brothers. Two of them were soldiers, the other was an abbot.
Since the family name of his mother came with some prestige, and was also known at court, Charles did not go to Paris as a "de Batz de Castlemore" he went as d'Artagnan. He is  also nephew to Henri de Montesquiou, Comte d'Artagnan. His uncle was friends with a certain Jean-Armand du Peyrer, Comte de Troisville or Tresville, he was an officer of the Regiment des Gardes Francaises, who then joined the Mousquetaires de la Garde, they were created as bodyguards for Louis XIII and originally consisted of 100 men, members of nobility who previously served in the army, armed with swords and muskets. D'Artagnan acted as carrier of secret messages between Cardinal and his allies and carried secret missions out. D'Artagnan was made lieutenant in the Regiment des Gardes Francaises in 1652, one year later Mazarin granted him the office Capitaine Concierge de la Voliere du Roi. Another year later, in 1654, d'Artagnan nearly got killed during the Battle of Stenay. He also participated in the sieges at Lancrecies and Sainte-Ghislaine.

In 1654 Monsieur d'Artagnan sold his previous charges and with 4,000 livres, pounds got himself the position of Captain.
In 1667 Mazarin decided to bring the Musketeers back, this time 150 men strong.

He met a rich widow and married the lady, Anne Charlotte de Chanlecy, dame de Sainte -Croix, became his wife on April 3, 1659 and their first child was born the following year. It was a son and named Louis in honor of the King.
Another son followed in 1661 and ws also named Louis.

D'Artagnan was killed on June 25, 1673 at the Siege of Mastricht, either by a musket bullet ripping his throat open or hitting his kidney. He was sadly mourned by the Musketeers and Louis XIV was filled with grief. The King wrote to the Queen the same day. "Madame I have lost d'Artagnan, in whom I hd utmost confidence and who merited it all occasions."