 Despite his great success and fame throughout his lifetime, his work, like that of the other Belgian Romantic painters, was quickly forgotten in the 20th century.He had many students, including Léon Abry, Aloïs Boudry, Edgard Farasyn, Godfried Guffens, Edouard Hamman, Joseph Lies, George Du Maurier, Karel Ooms, Ferdinand Pauwels, , Jan Swerts, Eliza Turck, , Jan Verhas, Frans Verhas and Charles Verlat.De Keyser was an extremely prolific painter and is said to have produced more than 350 paintings.