From: http://www.lwl.org/westfaelischer-friede/wfe-t/seitenanfang#seitenanfang:

No other artist of the 17th century dealt with peace so intensively in his work as did Peter Paul Rubens. Nor was there another who himself labored so tirelessly for peace: for over a decade, from 1623 to 1635, Rubens served as a diplomat, first under cover of his artistic activities during secret peace negotiations in the Netherlands and later as an official delegate in London, where he arranged a peace treaty in 1630. [2] Rubens was well-versed in international politics through his travels in Italy and Spain, Paris and London; his extensive correspondence in a number of languages bespeaks the wide range of his political, artistic, and intellectual contacts. As court painter to the Spanish regents of the Netherlands, the archducal pair Albert and Isabella, he had direct access to the court in Brussels.

...

Rubens' political goal of regaining prosperity through peace was formulated most urgently in the Pompus Introitus Ferdinandi. In this, the greatest pictorial program executed by Rubens for his home city, he was commissioned to provide decorations for the entry of the new Spanish governor of the Netherlands, the Cardinal Infante Ferdinand of Hapsburg, into Antwerp on April 16, 1635. [37] The solemn ceremonies with which the Netherlandish cities traditionally greeted their sovereigns and governors at the beginning of their reign had the highest civil and legal significance. In this way, the estates of the cities and provinces accepted the new rulers, who for their part confirmed the rights and privileges of the former. When the rebellious provinces broke with Philip IV of Spain in 1581, one of the reasons given was that he had violated the "Blijde Incomst," his oath at the ceremonial entry, and had become a tyrant. [38] The decorations at the governors' entries always included street theaters with allegorically formulated petitions to end the war and to bring back the "Golden Age," the flourishing of trade and craft. The situation of Antwerp, a center of world trade in the 16th century, had dramatically worsened since the Spanish conquest in 1585. The Hollanders had blockaded the mouth of the Scheldt and cut off the city's access to the sea, while foreign trade companies increasingly shifted their business to Amsterdam. Spain limited trade through tolls and excluded its loyal Netherlandish subjects from overseas trade with India and America. [39] It was above all with respect to these problems that Antwerp hoped for help from its new governor.

The overall direction for the program of triumphal arches, stage architectures, and tableaux vivants was entrusted to mayor Nicolas Rockox, the scholar and city secretary Caspar Gevaerts, and Rubens. Of the paintings from the Rubens workshop, only parts and fragments have survived, along with preparatory oil sketches. In 1642, Gevaerts published a complete description with extensive explanations and etched illustrations, one of the most elaborate publications of such an Intrede ever made.

The title page later designed for this publication [40] indicates the theme and mode of representation that informs the entire program: an homage to the Cardinal Infante in the context of Spanish rule, architecturally articulated and provided with allegorical commentary, in which the panegyric elements revolve around the proving of the ruler in war and peace. The portico is crowned with a portrait of the Spanish king Philip IV, with the star Hesperus (Venus) symbolizing that "the sun never sets" on his empire. The main image shows the transfer of the regency; below it, an inscription devised by Gevaerts formulates the ruler's duty: "Thou who rulest Belgium, consider: spare those who submit, but break the defiance of the rebels." [41] The herms that support the building are associated with war and peace: to the left stand Victoria and Mars, to the right Mercury and Pax with the inscription "Peace is the highest good."

From: http://www.geocities.com/Paris/9974/4pm.htm

Rubens diary, April 2nd 1632, 4 P.M.

"For a couple of hours I went on making a portrait of a very good friend of mine, Gaspar Gevaert, generally called Gevartius, being a philosopher and a writer.
I admire this man for his extraordinary erudition and I am very thankful for what he did for me, especially for my children, when I was abroad about two years long.

In 1628, when I was a widower, our regent Isabella, whose court-painter I am and with whom I have a close relationship, begged me to be helpful in an important political question: be a diplomat for a while and assist at peace-negociations between Spain and England. I agreed and went to Madrid first to be initiated, later to London where the discussions took place.
Someone had to care for my two sons Albert and Nicolas. Mr. Gevaert did so; he was their second father then and he personally educated them perfectly.

Note:

In connection with Rubens, this Gevartius is known as the author who wrote the comments in a famous volume, edited at Plantin's Office, Antwerp, representing in detail all the arches of triumph decorating the streets of Antwerp in 1635, when a new regent was welcomed.

It was Rubens who made all the oil-sketches representing the arches, richly decorated with paintings and sculptures; many collaborators executed, under supervision of the master. The drawings for the engravings, represented in that book (called: "Pompa introitus Ferdinandi") were made by one of Rubens' pupils: Theodore Van Thulden.

The portrait of Gevartius by Rubens now is in the Antwerp Museum of Fine Arts.