thumb|220px|Self-portrait, 1675
Jacques Courtois () or Giacomo Cortese, called il Borgognone or le Bourguignon (12 ?December 162114 November 1676) was a Franche-Comtois–Italian painter, draughtsman, and etcher. He was mainly active in Rome and Florence and became known as the leading battle painter of his age. He also created history paintings and portraits. He became a Jesuit later in life while continuing to paint.
Life
Jacques Courtois was born in Saint-Hippolyte, near Besançon (Franche-Comté) in present-day France, but at the time, a Spanish possession in Holy Roman Empire. He was the son of the obscure painter Jean-Pierre Courtois. Very little is known about Guillaume’s youth but it is assumed he received his initial training from his father. He had two younger brothers who also became painters Guillaume (Guglielmo Cortese) (1628 - 1679) and Jean-François (c. 1627-?). As his brother was later also known as 'il Borgognone' (a reference to their origins in Burgundy, called Comté de Bourgogne or Franche-Comté in French), some of the works of the brothers have been confused.
thumb|300px|left|Storming of a castle
The father took his sons to Italy around 1636 when they were still young. They first travelled to Milan. According to contemporary biographers he served for three years in the Spanish army. During this time he drew marches and battles, fight scenes, landscapes and military costumes. After leaving the army, he studied for some time in Milan with an unidentified sculptor. He moved to Bologna in 1639 where he first entered the studio of Jérôme Colomès, a painter from Lorraine. According to early Italian biographer Filippo Baldinucci Courtois' talent got noticed in Bologna by prominent painters Guido Reni and Francesco Albani. He continued his apprenticeship in Siena, where he studied for some time at the school of Astolfo Petrazzi.
thumb|300px|Battle between European troops
It is possible that the brothers Guillaume and Jacques remained together until the late 1640s. He stayed for a short time in Florence where he met two Northern painters Jan Asselijn, a battle painter, and Matthieu van Plattenberg (known as ' Monsù Montagna'), a marine artist.
He went to Rome around 1639-1640 where he initially was permitted to live in the monastery of Santa Croce in Gerusalemme in Milan through the intercession of the abbot Don Ilarione Rancati. The abbot was instrumental in securing Courtois' first official commissions, a large fresco of the miracle of the loaves and fishes in the refectory of the monastery (1641). The style of genre painting practiced by Pieter van Laer was followed by other Northern and Italian painters. These followers became known as the Bamboccianti and a painting in this style as a Bambocciata (plural: Bambocciate). Michelangelo Cerquozzi, the leading battle painter in Italy in the first decades of the 17th century who also painted genre paintings in the style of the Bamboccianti, recognized Courtois' talent and encouraged him to paint battle scenes. Courtois was called to enter the service of Prince Mattias de' Medici, the then governor of Siena and brother of Ferdinando II de' Medici, Grand Duke of Tuscany. The Prince unsuccessfully tried to reconcile the spouses. The couple did not reunite when Courtois returned to Rome later that year.
thumb|300px|left|Rocky valley
After the death of his wife in 1654, Jacques Courtois had to deal with the family property and provide dowries for two of his sisters who were Ursuline nuns in Fribourg, Switzerland. He also made some religious pictures for their convent.
In 1668 he became a priest.
War art
thumb|300px|Battle Scene with Turkish Cavalry
Courtois painted imaginary as well historical battles drawn from various episodes of the Thirty Years' War. Draw from his own firsthand experience of wartime facts and techniques, he succeeded in giving his visual representations the impression of 'truthfulness'. Regarded as one of the great battle painters of the 17th century, he was referred to as the 'Raphael of battles' and the 'Prince Eugene of painters'. Prince Eugene was one of the most successful military commanders in modern European history. His paintings of battles were so popular that no large or small collection of his time was without a work by his hand.
Jacques Courtois was known for working alla prima starting from rapid pen sketches. This approach to painting echoed the dynamism of his battle scenes that established his fame. His sketch-books (London British Museum, and Florence, Gallerie Uffizi) demonstrate his acute ability to capture in quick sketches the movements and the dynamics of troops, while using compositional schemes, which were derived from the work of Jacques Callot. His drawings also show the influence of Stefano Della Bella.