Leys' study of 16th-century Flemish and German painters also contributed to the development of a personal style, which mingled archaistic rigidity with realistic observation. With these works, he earned a following among many younger artists in Belgium as well as a considerable reputation in France, where he won a gold medal at the International Exhibition in Paris in 1855 for his historical painting "The Mass of Berthal de Haze" (Royal Museums of Fine Arts of Belgium, Brussels). Leys was a gifted portrait painter as shown by his self-portrait, and the portraits of his and daughter and of his fellow artists such as the portrait of the architect . Leys influenced many young Belgian artists. Some, such as Joseph Lies, Franz Vinck and Karel Ooms followed his work very closely. Leys' work also exerted a strong influence on his compatriots Jean Pierre François Lamorinière and Victor Lagye. James Tissot was influenced by Leys in his early work. Other artists such as Henri De Braekeleer and Jan Stobbaerts were able to transform Leys' teachings in a new and original language.