In 1935, the archaeologist Willem Frederik Stutterheim[2] of the Oudheidkundige Dienst in Nederlandsch-Indië (Archaeological Service in the Netherlands Indies) gave a lecture at the University of Amsterdam at which time he advised de Casparis to transfer to Leiden to continue his studies because the Oudheidkundige Dienst was looking for an epigrapher to replace Roelof Goris.
He excelled as a student and quickly passed his examinations in Sanskrit (with Jean Philippe Vogel), Avestan (with J. H. Kramers), archaeology and ancient history (with N. J. Krom), Old Javanese (with Cornelis Christiaan Berg), and Malay (with Ph.
With the imperial Japanese threat, he was called up on 2 July 1940 to serve as a cryptographer in the Dutch colonial army (KNIL) and in the same year Louis-Charles Damais succeeded him as acting epigrapher.
At this time, some seven years after first meeting his future wife in France while en route to Batativa, he married Gisèle Marie Fongaro, an Italian-born Frenchwoman.
The Renville Agreement paved the way for de Casparis's return to the archipelago in 1948 and a year later, his wife and young daughter Anna (born 1947) followed him to Jakarta.
As of November 1947, August Johan Bernet Kempers headed the Oudheidkundige Dienst and on 17 April 1948, De Casparis again took up his post as epigrapher.
In 1955, de Casparis became professor in the early history of Indonesia and Sanskrit at a branch of Airlangga University (Surabaya) in Malang.
In the same year he also gave courses as visiting professor of the history of South and Southeast Asia at Universitas Adityawarman, founded by Mohammad Yamin in Batusangkar, Sumatra.
Many of his students were from Sri Lanka, and this led to his being awarded a Doctor of Letters, honoris causa, by the University of Peradeniya on 22 December 1990.