This Estates General assembly was delayed until Louis XIII formally came of age on his thirteenth birthday. Although Louis's coming of age formally ended Marie's Regency, she remained the de facto ruler of France. The Estates General accomplished little, spending its time discussing the relationship of France to the Papacy and the venality of offices, but not reaching any resolutions.

Beginning in 1615, Marie came to rely increasingly on Concino Concini, who now assumed the role of her favourite. Concini was widely unpopular because he was an Italian, and therefore a foreigner. This further antagonised Condé, who launched another rebellion in 1616. Huguenot leaders supported Condé's rebellion, which led the young Louis XIII to conclude that they would never be loyal subjects. Eventually, Condé and Queen Marie made peace via the Treaty of Loudun, which allowed Condé great power in government, but didn't remove Concini. With growing dissatisfaction from nobles due to Concini's position, Queen Marie, with Louis' help, imprisoned Condé to protect Concini, leading to renewed revolts against the Queen and Concini.

In the meantime, Charles d'Albert, the Grand Falconer of France, convinced Louis XIII that he should break with his mother and support the rebels. Louis thus organised a palace coup d'état. As a result, Concino Concini was assassinated (24 April 1617) and Marie was sent into exile in Blois. Louis created Charles d'Albert, his new favourite, the first duke of Luynes.

Luynes soon became as unpopular as Concini had been. Other nobles resented what they saw as Luynes's monopolisation of the King. Luynes was seen as not as competent as Henry IV's ministers, who had surrounded Marie de' Medici, and who were now dying off.

The Thirty Years' War broke out in 1618. The French Court was initially unsure what side to support. On the one hand, France's traditional rivalry with the House of Habsburg argued in favour of intervening on behalf of the Protestant powers (and Louis's father Henry IV of France was once a Huguenot leader). On the other hand, Louis XIII had had a strict religious Catholic upbringing, and his natural inclination was therefore to support the Catholic Holy Roman Emperor, Ferdinand II.

The French nobles were further antagonised against Luynes by the 1618 revocation of the paulette tax and by the sale of offices in 1620. From her exile in Blois, Marie de' Medici became the obvious rallying point for this discontent, and the bishop of Luçon was allowed to act as her chief adviser, serving as a go-between to Marie and the King.

French nobles launched a rebellion in 1620, but their forces were easily routed by royal forces at Les Ponts - de - Cé in August 1620. Louis then launched an expedition against the Huguenots of Béarn who had defied a number of Royal decisions. This expedition managed to re-establish Catholicism in Béarn. However, the Béarn expedition drove Huguenots in other provinces into a rebellion led by Henri, duc de Rohan.

In 1621, Louis XIII was formally reconciled with his mother. De Luynes was created Constable of France and Louis and Luynes set out to quell the Huguenot rebellion. The siege at the Huguenot stronghold of Montauban had to be abandoned after three months, owing to the large number of Royal troops who had succumbed to camp fever. One of the victims of camp fever was Luynes, who died in December 1621.

Following the death of Luynes, Louis determined that he would rule by council. His mother returned from exile and, in 1622, entered this council where Henry II de Bourbon, prince de Condé recommended violent suppression of the Huguenots. The 1622 campaign, however, followed the pattern of the previous year: Royal forces won some early victories, but were unable to complete a siege, this time at the fortress of Montpellier.

The rebellion was ended by the Treaty of Montpellier, signed by Louis XIII and Henri, duc de Rohan, in October 1622. The treaty confirmed the tenets of the Edict of Nantes: several Huguenot fortresses were to be razed, but the Huguenots retained control of Montauban and La Rochelle.

Louis ultimately dismissed Noël Brûlart de Sillery and Pierre Brulart, vicomte de Puisieux, in 1624 because of his displeasure with how they handled the diplomatic situation over the Valtellina with Spain. Valtellina was an area with Catholic inhabitants under the suzerainty of the Protestant Three Leagues. It served as an important route to Italy for France and also it provided an easy connection between the Spanish and the Austrian Habsburg Kingdoms, especially in helping each others with armies if necessary. Spain was constantly interfering in the Valtellina, which angered Louis as he wanted to hold possession of this strategically important passageway. (At these years the French Kingdom was literally surrounded by the Habsburgs as they were the Kings of Spain and Austria. In addition, these empires included the territories of today's Belgium, the Netherlands, parts of Germany and Northern Italy.)

Cardinal Richelieu played a major role in Louis XIII's reign from 1624, decisively shaping the destiny of France for the next eighteen years. As a result of Richelieu's work, Louis XIII became one of the first examples of an absolute monarch. Under Louis and Richelieu, the crown successfully intervened in the Thirty Years' War against the Habsburgs, managed to keep the French nobility in line, and retracted the political and military privileges granted to the Huguenots by Henry IV (while maintaining their religious freedoms). Louis XIII led successfully the important Siege of La Rochelle. In addition, Louis had the port of Le Havre modernised, and he built a powerful navy.

Unfortunately, time and circumstances never permitted the King and the Cardinal to attend to the administrative reforms (particularly of France's tax system) which were urgently needed.

Louis also worked to reverse the trend of promising French artists leaving for Italy to work and study. He commissioned the painters Nicolas Poussin and Philippe de Champaigne to decorate the Louvre. In foreign matters, Louis organised the development and administration of New France, expanding its settlements westward along the Saint Lawrence River from Quebec City to Montreal.

In order to continue the exploration efforts of his predecessor Henry IV, Louis XIII considered a colonial venture in Morocco, and sent a fleet under Isaac de Razilly in 1619. Razilly was able to reconnoiter the coast as far as Mogador. In 1624, he was put in charge of an embassy to the pirate harbour of Salé in Morocco, in order to solve the affair of the library of Mulay Zidan.

In 1630, Razilly was able to negotiate the purchase of French slaves from the Moroccans. He visited Marocco again in 1631, and participated to the negotiation of the Franco - Moroccan Treaty (1631). The Treaty gave France preferential treatment, known as Capitulations: preferential tariffs, the establishment of a Consulate and freedom of religion for French subjects.

Acadia was also developed under Louis XIII. In 1632, Isaac de Razilly became involved, at the request of Cardinal Richelieu, in the colonization of Acadia, by taking possession of the Habitation at Port - Royal (now Annapolis Royal, Nova Scotia) and developing it into a French colony. The King gave Razilly the official title of lieutenant - general for New France. He took on military tasks such as ordering the taking of control of Fort Pentagouet at Majabigwaduce on the Penobscot Bay, which had been given to France in an earlier Treaty, and to inform the English they were to vacate all lands North of Pemaquid. This resulted in all the French interests in Acadia being restored.

In Brazil, the colony of Equinoctial France was established in 1612, but only lasted 4 years until it was eliminated by the Portuguese.

France - Japan relations started under Louis XIII in 1615 when Hasekura Tsunenaga, a Japanese samurai and ambassador, sent to Rome by Date Masamune, landed at Saint - Tropez for a few days. In 1636, Guillaume Courtet, a French Dominican priest, would reciprocate when he set foot in Japan.

The same year, in 1615, the regent Marie de Médici incorporated the merchants of Dieppe and other harbours to found the Company of the Moluccas. In 1619, an armed expedition composed of three ships (275 crews, 106 cannons) and called the "Fleet of Montmorency" under General Augustin de Beaulieu was sent from Honfleur, with the objective of fighting the Dutch in the Far East. Finally in 1624, with the Treaty of Compiègne, Richelieu obtained that the Dutch would stop fighting the French in the East.

On two occasions the King's younger brother, Gaston, Duke of Orléans had to leave France for conspiring against the King's government, and for attempting to undermine the influence of both his mother and of Cardinal Richelieu. After waging an unsuccessful war in Languedoc, he took refuge in Flanders. In 1643, on the death of Louis XIII, Gaston became lieutenant - general of the kingdom, and fought against Spain on the northern frontiers of France.

On 24 November 1615, Louis XIII married Anne of Austria, daughter of Philip III of Spain. This marriage followed a tradition of cementing military and political alliances between the Catholic powers of France and Spain with Royal marriages. The tradition went back to the marriage of Philip II of Spain with the French Princess, Elisabeth of Valois. The marriage was only briefly happy, and the King's duties often kept them apart. After twenty - three years of marriage and four miscarriages, Anne finally gave birth to a son on 5 September 1638, the future Louis XIV.

Many regarded this birth as a divine miracle and, in show of gratitude to God for the long awaited birth of an heir, his parents named him Louis - Dieudonné (“God - given”). As another sign of gratitude, according to several interpretations, seven months before his birth, France was dedicated by Louis XIII to the Virgin Mary, who, many believed, had interceded for the perceived miracle. However, the text of the dedication does not mention the royal pregnancy and birth as one of its reasons. Also, Louis XIII himself is said to have expressed his scepticism with regards to the miracle after his son's birth. In gratitude for successfully given birth the queen founded the Benedictine abbey of the Val - de - Grâce, for which the Louis XIV himself laid the cornerstone of its church, an early masterpiece of French Baroque architecture.

It is said that when the king lay on his deathbed the queen brought Louis (who was not yet five years old) to see his father. The young Louis could already grasp the reality of the situation because when his father asked his son if he knew who he was, the young Louis answered, "Louis the Fourteenth, Father." To which his father responded, "You are not Louis the Fourteenth, yet."
There is no evidence that Louis had mistresses (consequently earning the title of 'Louis the Chaste'), but persistent rumours insinuated that he may have been homosexual or at least bisexual. Tallemant des Réaux, drawing from rumours told to him by a critic of the king (the marquise de Rambouillet), explicitly speculated in his Historiettes what happened in the King's bed. A liaison with an equerry, François de Baradas, ended when the latter lost favour fighting a duel after duelling had been forbidden by royal decree. He was also allegedly captivated by Marquis de Cinq-Mars, who was later executed for conspiring with the Spanish enemy in time of war. Tallemant described how on a Royal journey, the King "sent M. le Grand [de Cinq-Mars] to undress, who returned, adorned like a bride. 'To bed, to bed' he said to him impatiently... and the mignon was not in before the King was already kissing his hands."