Afterwards Šimon started to work with renewed energy and added two new techniques, the mezzotint and wood-cut. In the summer of 1914 while the Šimons were again in Prague the archduke Ferdinand was assassinated in Sarajevo and a war broke out that turned out to become the World War I. The return to France became impossible. The painter was not drafted in the Austrian army but the livelihood of an artist became rather difficult as war years dragged on. In August 1926 Šimon was able to fulfill his long-held dream of traveling around the world and broadening his repertoire by visiting the more distant parts of the world. He was
regularly writing long letters to his wife describing his experiences and impressions, often illustrated with pencil sketches. From New York the tour then proceeded to Boston, Buffalo, Pittsburgh, Cleveland, Detroit, Chicago, Washington, Philadelphia, San Diego, Los Angeles, San Francisco, after which he continued to Hawaii and the Philippines, Japan, China, Hong Kong, Sri Lanka, then called Ceylon, India, Egypt, and Greece, ending with Naples and Marseille.
The Orient made a great impression on the artist and he responded by producing numerous etchings, aquatints and oil paintings, some of which were shown at a comprehensive exhibit in Prague on the occasion of Šimon's 50th birthday. In 1928 Šimon was appointed a professor at the Academy of Arts in Prague to head the school of graphic arts. After 1930 his work as a professor, curator and writer took too much of his energy, and it is regrettable he had too little time for his artistic work. Arthur Novak in 1937 made a list of the graphic works of T.F. Simon and he listed a total of 626 pieces. Then the Academy was closed
in November 1939 after the Nazi occupation of Czechoslovakia. Šimon took very hard the events of World War II and stress declined his health seriously. He died at home by heart failure following a heart attack some months earlier.