How did Peter Paul Rubens use his fame as a painter during diplomatic missions?

Peter Paul Rubens leveraged his immense reputation as "the painter of princes and the prince of painters" to facilitate his work as a diplomat. His fame allowed him to travel freely between royal courts, providing him with access to sovereigns and their ministers for discreet meetings.1

During these diplomatic missions, Rubens often utilized the time spent painting portraits of these leaders to discuss sensitive matters of state. His status was so significant that when he traveled to England to negotiate a peace treaty between England and Spain, King Charles I was eager to meet him specifically due to his international reputation for intellect and artistic genius. To ensure Rubens held the appropriate standing for these high-level negotiations, King Philip IV of Spain even granted him the title of "secretary of the king’s privy council of the Netherlands".1

Ultimately, Rubens’s ability to navigate these elite circles was instrumental in his success; he is personally credited with the peace treaty of 1630 between England and Spain.1