In 1894, he organized a large popular assembly in Sibiu that protested against the government's decision to ban the Romanian National Party.

[1] In August 1916, in the middle of World War I and days before the Romanian Old Kingdom entered the conflict against Austria-Hungary, Mangra was elected Metropolitan of Transylvania.

Shortly after the election, Romanian troops entered Transylvania, forcing a number of institutions to withdraw into the interior of the monarchy.

These included the Sibiu-based archdiocesan council and theological institute, which functioned at Oradea from September 1916 until the following June,[2] when Mangra was able to take up residence at Sibiu.

[3] Thus, his enthronement took place in Oradea in October 1916;[2] the rite was performed by suffragan bishops Ioan Papp of Arad and Miron Cristea of Caransebeș.

In the summer of 1917, Education Minister Albert Apponyi ordered that a ministerial employee with full rights over the activities of teachers and students be assigned to each Romanian pedagogical school.