In 1878 Matejko painted another picture meant to "put heart" into the Poles. This was The Battle of Grunwald, which recalled one of the most important events in Polish history, that is, the defeat of the power of the Teutonic Knights.

On 15 July 1410, on the battlefield of Grunwald, the united Polish, Lithuanian and Ruthenian forces under King Ladislaus Jagiello routed the Teutonic Knights who had been a threat to both Poland and Lithuania.

It took Matejko three years to complete The Battle of Grunwald. The canvas, brought from France, was one huge piece with no seams, measuring 997 by 426 cm. It is the largest of Matejko's paintings and it is regarded as a masterpiece of battle scene painting. It is, as it were, a cross-section through a swirling mass of knights and horses intertwined in mortal struggle. Two figures are brought into relief: the Grand Master of the Teutonic Order, Ulrich von Jungingen, about to be killed by two young Lithuanian warriors, and the Grand Duke of of Lithuania, Viatautas, galloping, his naked sword raised high. The scene is depicted dynamically and with painstaking attention to detail.
On 28 September 1878, the exhibition of The Battle of Grunwald opened in Cracow. Crowds came to see the painting, and the takings exceeded three thousand guldens, a large amount at that time. As reviewers noted, there were crowds in the picture and crowds in front of it. In appreciation of his achievement, Matejko received the symbolic sceptre of the arts from the Cracow council.
In April 1882, the artist completed his next painting aimed at giving courage to his fellow countrymen, The Prussian Homage. [*]