 Bossert was born in Landau, German Empire, on September 11, 1889.He was educated in history of art, history, archaeology and German studies at the universities of Heidelberg, Strasbourg, Munich and Freiburg im Breisgau.In 1913, he was awarded the title PhD by University of Freiburg with a thesis on "Der ehemalige Hochaltar in Unserer Lieben Frauen Pfarrkirche zu Sterzing in Tirol" ("The former high altar in the Parish of "Our Lady of Marsh" to Sterzing in Tyrol).