In recognition of his services he was made Canon of Strasbourg, and, shortly before his death, historiographer royal for Alsace.
His forte was critical investigation, but his intense application soon undermined his health, and he died at the early age of thirty-four at Lucelle Abbey in the Sundgau.
From the manuscripts of Grandidier, Liblin continued this monumental work under the title: Oeuvres historiques inédites de Ph.-A.
Pius VI expressed his admiration of Grandidier's work and encouraged the young man to further labours.
The other canons of Strasbourg, feeling slighted, opposed Grandidier's scientific methods, even questioning the soundness of his faith, and for a while he dropped all historical work.