Further, Theobald's right to the succession was challenged by Henry's daughter Philippa and her husband, Erard I of Brienne, Count of Ramerupt, and one of the more powerful nobles of Champagne.

Twenty-six barons accepted Louis VIII's new measures, but Theobald IV did not, since he had an agreement with the Jews that guaranteed their safety in return for extra income through taxation.

Theobald IV's refusal to enact Louis VIII's new antagonistic policies towards the Jews enlarged a growing feud between the two men.

During the siege of Avignon in 1226, part of the Albigensian Crusade, due to his disagreements with the king, Theobald IV performed only the minimum service of 40 days and then went home.

At the beginning of the regency of Blanche of Castile, he abandoned a conspiracy against the French king, which also included Hugh X of Lusignan and Peter I of Brittany,[3] and cemented a strong relation with the regent.

Strong rumors began to spread that Theobald IV was having an affair with Louis VIII's widow, the regent Blanche of Castile, for whom he composed a poetic homage.

Wendover claims that Theobald, "tormented by passion" for the queen, tried to poison King Louis VIII at the siege of Avignon.

In general, the other barons were jealous of the strengthened County of Champagne which had emerged from the Succession War, and now presented a major rival to surrounding areas.

The conflict with the County of Bar prompted the more powerful Duchy of Burgundy to invade Champagne from the south, led by Duke Hugh IV (his father Odo III, Blanche of Navarre's staunch ally, had died in 1218).

The situation reached its nadir in 1233, when Henry II's elder daughter Queen Alice of Cyprus threatened to reprise the succession war of Theobald IV's minority yet again.

The lords and barons of Northern France who had been in conflict with Theobald IV in 1229 left him in peace, realizing that as the new king of Navarre, his position was too strong to challenge.

He entrusted most of the government to nobles of Champagne and divided Navarre into four new districts based on fiscal functions and maintenance of public order.

The next year, Theobald engaged his daughter to John I, Duke of Brittany, the son of his close crusading ally Peter of Dreux.

He spent much time dallying at pleasant Acre (where he wrote a poem to his wife) before moving on Ascalon, where he began the construction of a castle.

Whilst marching the crusader army to Ascalon, a contingent of 400 knights led by Hugh of Burgundy, Henry of Bar, and Amaury de Montfort chose to engage Muslim forces at Gaza.

He refused to respond to papal tribunals, but Pope Innocent IV conceded him the privilege of kings: nobody could excommunicate him save the Holy See.