He took part in the war of the succession of Champagne and supported the claims of his cousin Érard of Brienne against Countess Blanche of Navarre and her son, the future Thibaut IV.

Upon returning to France, he entered into a prestigious marriage with Alix de Dreux, his second wife, who hailed from Capetian lineage and was the lady of Traves.

In 1228, he joined forces with Count Thibaut IV of Champagne in a battle against a coalition led by a half-brother of the king who was dissatisfied with Queen Mother Blanche of Castille's regency.

He sought to enhance the influence of his house while preserving independence from neighboring powers such as the counts of Burgundy, Champagne, and Bar.

Renard is consistently mentioned alongside his father in various documents over the following decade, indicating his involvement in power matters and his apprenticeship.

[2] The only document mentioning Renard's presence in Messina in 1190 is a forgery created for establishing the Hall of Crusades at the Palace of Versailles.

Historian Gilles Poissonnier suggests that Renard was born in 1175 or 1176, making him around fifteen years old at the time of the supposed crusade.

The lordship of Faucogney was then held by his eldest son, Aymon, who died around 1205 without marrying or having children, thus passing the family estate to his sister, Clémence,[Note 2] and subsequently to her husband.

He initially shared management of the estate with his mother Alix of Vignory, who had usufruct over the property, possibly as part of her dower.

He was the first in his lineage to employ personal scribes from the start of his rule, enabling him to break free from episcopal oversight while remaining a vassal of the Bishop of Langres.

[P 6] As the lord of Choiseul, he was responsible for providing dowries for his sisters and arranging marriages to form alliances with other noble houses.

[P 4] However, Choiseul was an independent fief that only paid homage to the Bishop of Langres, despite being a target of interest for its neighbors, the counties of Bar and Champagne.

[P 8] In 1214, he was one of the knight bannerets who gathered under the banner of the Count of Champagne in response to the call of the King of France, Philip Augustus.

[G 2][F 3] In 1217, Pope Honorius III urged Érard of Brienne and his supporters, including Renard, to reconcile with Blanche of Navarre or face excommunication.

[A 3] However, hostilities resumed, leading Pope Honorius III to excommunicate Érard of Brienne and his allies, including Renard.

This marriage was significant for the house of Choiseul as Alix of Dreux was a descendant of King Louis VI of the Franks, making her of Capetian origin.

[P 15] The efforts to reclaim his wife's property proved costly for Renard, leading him to borrow 250 pounds from Gilebert of Chaumont in 1223, a wealthy bourgeois, and offering the village of Chauffourt as collateral for the loan repayment.

However, they were met with a cold reception and were unable to access their portion of the inheritance from Gaucher IV of Mâcon, who was Alix of Dreux's first husband.

This was likely due to interference from Marguerite of Salins, the eldest daughter of Gaucher IV of Mâcon, and his first wife Mathilde of Bourbon.

After spending several months at Bracon without any progress,[F 4] they decided to sell their share of the inheritance to the Duchess of Burgundy and returned to Bassigny.

[A 8] However, Count of Champagne Theobald, loyal to Queen Mother Blanche of Castille, raised an army of 300 horsemen, including Renard, to defend the young king.

[P 12] This arrangement placed Renard under the protection of the three neighboring counties, preventing any of them from attempting to seize Choiseul without facing potential retaliation from the other two.

For instance, he allocated a third of the new crops to the priory of Varennes in exchange for their assistance in clearing the forest for new agricultural areas, leading to the settlement of new peasants and increased tax revenue.

[P 11] In 1220, he attended the court of the Duchess of Burgundy, Alix of Vergy, where he witnessed her promise to uphold the privileges of the commune of Dijon.

[P 15] In 1236, he took part in the signing of the marriage contract between his nephew John of Brittany and Blanche of Champagne, the daughter of Count Theobald I, at Château-Thierry.

[P 3] Chardin of Croisilles, who had previously been in the company of Count Érard II of Brienne, was warmly welcomed and composed a few verses in his honor:[A 9] To Choiseul go, song, with great cheer, And tell Renaud that every day, immeasurably, I love him loyally and with a whole heart, For praise and honor will greatly reward him.

He mocked the ladies of Choiseul and Châteauvillain, accusing them of being spendthrifts, and criticized the lords for not welcoming troubadours generously.