He joined the king's expedition to Italy, fighting at the Battle of Pavia as a page of Anne de Montmorency.

In the wake of the disaster, with the capture of the king, Sansac was also made prisoner, however he was able to escape and worked alongside the regent in the conducting of negotiations with the Spanish the result of which was the Treaty of Madrid.

[4] As royal authority continued to crumble with the outbreak of open civil war, Sansac asked to be relieved of his office in September 1562.

[5] With François, Duke of Guise assassinated at the climax of the first war of religion, the perpetrator Jean de Poltrot was quickly apprehended.

[7] With the Peace of Longjumeau having concluded the second civil war, Sansac was among those royal councillors, aligned with Lorraine in their desire to overturn it.