In 1428, Joan's "voices" commanded her to travel to Vaucouleurs, a nearby fortress still loyal to the Dauphin. Knowing her parents would forbid her to go, Joan lied to her parents and told them she was leaving to help a neighbor's wife give birth. Joan found the captain of the fortress and asked him to let her join the Dauphin. He did not take the sixteen-year-old peasant girl seriously, however, laughing at her and sending her home to Domremy. In 1429, Joan returned to the fort at Vaucouleurs. For unknown reasons, the captain was persuaded by her earnestness this time. On February 13, 1429, Joan and her small military escort set out from Vaucouleurs to travel to the Dauphin's castle at Chinon. Joan now began wearing men's clothes to make herself less conspicuous as she traveled through English-controlled territory.

When she arrived in Chinon, the Dauphin hesitated to see Joan. But two days after her arrival at Chinon, the Dauphin finally agreed to grant Joan an audience. According to legend, even though the Dauphin had secretly hidden himself among his court for security reasons, Joan immediately walked right up to him (though she had never seen him before) and pledged to help him defeat the English and see his coronation at Reims as France's true king. Charles sent Joan to be interrogated by churchmen, since her claim to hear commands from God smacked of possible heresy or witchcraft. For three weeks, ecclesiastical experts questioned Joan at Poitiers.

Joan's greatest support in the Dauphin's court came from the Duke of Alencon, who ultimately persuaded the Dauphin to take Joan up on her offer. In April, at Tours, the Dauphin gave Joan command of a small military unit, essentially giving her the military power of a knight. She even had her own squire, Jean of Aulon, and her own crest and banner, which were to remain inspirational symbols to the Dauphin's forces over the next two years. Regarding her sword, Joan's "voices" told her that a magical and holy sword would be found in the Church of Saint Catherine of Fierbois. Indeed, a sword was found there, and was given to Joan. Although it is unclear exactly how many men Joan commanded, their numbers likely totaled several hundred.

On April 27, 1429, Joan set out from Blois to reinforce the Dauphin's troops at the Siege of Orleans. Orleans had been under siege by the English since 1428. Joan and another of the Dauphin's commanders named La Hire reached Orleans on April 29, 1429. La Hire said to wait for all the reinforcements to arrive, and Joan initially obeyed, until she heard a new command from her "voices."

By 1427, five years after his father had died and he had taken over the reign, Charles still had not been officially crowned. For this reason Joan continued to call him the "Dauphin" (the name for the heir apparent to the French throne). The traditional coronation place for French kings, where the container of sacred anointing oil was stored, was the Cathedral at Reims. Reims, however, was controlled by the allied armies of England and Burgundy, who dominated Northern France in this period of the Hundred Years' War. The coronation seems to have been a much bigger issue for Joan than for most other people. The majority of the nation already called Charles "King Charles VII". But it was in following her obsession that Joan became a national symbol, helping to unify France and ending of the Siege of Orleans.

Joan's white lies to her parents regarding her reasons for departing from Reims contrasts with the traditional view of Joan as the perfect and pure heroine. Here we see her as a willful daughter resisting her parents' authority and deceptively sneaking away from home to go on an adventure. Moreover, after taking up arms, Joan began to make herself out in the most colorful and expensive male garb she could find, contrary to the standard view of her as the simple Christian warrior. Was this the result of vanity, or was she considering how best to make a fearsome figure, a more powerful political impact?

The Dauphin initially hesitated to receive Joan, whom he initially suspected was crazy. Still, the Dauphin was desperate for help and although his advisors disagreed over whether or not to hear Joan, he eventually relented. Certainly he was a bit frightened of the strange young woman, whose stories seemed to suggest witchcraft. Fortunately for his own sake, however, the Dauphin decided to use Joan as best he could. For her part, Joan, although several years younger than the Dauphin, considered him so helpless as to compare him to a "child" who needed her protection.