The chapel is replacing so to speak a lacking, in this architectural arrangement, side aisle with the quadrangular bell tower built in the 17th century. It was given the title of Grunwald Chapel, due to the stucco bust of  Władyslaw Jagiello, the founder of the Church. Under this bust there is a granite plaque with the inscription:

THE CHURCH WAS ERECTED BY
THE KING  WŁADYSŁAW JAGIEŁŁO
IN MEMORANDUM OF THE VICTORY
IN THE BATTLE OF GRUNWALD 15 JULY 1410.
IN THE QUINCENTENARY
GRATEFUL POSTERITY PUT THIS PLAQUE

Next to the stone window above the Bust of the Monarch, there is Jagiellonian and Lithuanian flag, reminding of the combined forces of Polish and Lithuanian armies, which had won the Battle of Grunwald. In this chapel there is a neo-Gothic altar with a painting of Sistine Mother of God and a portrait of St. Juda-Thaddeus. This apostle is particularly honored in our temple and he is its patron, next to the Blessed Virgin Mary the Victorious and Saint Bridget.

Weekly Votive Mass in honour of St. Juda-Thaddeus is celebrated in this chapel at the mentioned altar (every Thursday, 8am). Intentions can be placed in the church to the can by the side altar or via the Internet. A sheet file should be download with an intention to St. Juda-Thaddeus, filled and sent. You can also light a light of gratitude. Paintings along with the side altar were transported in May 2012 to a conservation workshop for renovation. These renovation works were not a part of the EU project. Renovating these monuments was possible thanks to grants awarded by the Provincial Office of  the  Preservation of Monuments in Lublin, the Marshal's Office in Lublin and an anonymous donor. The work was carried out by AC Preservation of Monuments A. Piotrowski, E. Kosakowski from Cracow. Renovated movable monuments returned to their place at the jubilee celebrations of the 600th anniversary of the construction's beginning of the royal votive which took place in 2012. In the chapel there is also a picture of King Kazimierz Jagiellończyk, previously hanging on the right wall of the chancel (renovation of the image and the bust of the monarch was carried out in 2010). From the Chapel of Grunwald the door and the narrow passage lead to the sacristy, while the stairs to the ambo, located on the left of the main aisle.

In the Chapel, after renovation, there is also a glass window, allowing the view of the crypt made of white gothic stone with the exposure of 2 coffins of the Visitation Sisters. Renovation of the timber roof truss with replacement of the roof coating of  Juda-Thaddeus's chapel with the sacristy and the bridge was conducted by SMART-BUD company of Andrzej Król, thanks to the grant awarded by the Ministry of Culture and National Heritage in 2012. These renovations were outside the scope of the Project of Renovation of the post-bridgettines' monastic complex in the city centre of Lublin.