Introduction
Saint Nicasius of Rouen (French: Nicaise de Rouen; d. perhaps c. 260), often known as the Apostle of the Vexin, was a 3rd-century saint and martyr in Gaul. He is sometimes considered the first Bishop of Rouen, although probably incorrectly.
Life
Nicasius evangelized the Vexin, although he was apparently never in Rouen and despite tradition, was probably never bishop there. He spent a year at Mousseaux and evangelized Rolleboise nearby. He performed several miracles and evangelized numerous places along the Seine (among them Conflans, Andrésy, Triel, Vaux, Meulan, Mantes and La Roche-Guyon) but was martyred with his companions on the banks of the Epte in Gasny before reaching Rouen. He was believed to have been buried in Gasny.
Saint Mellon, possibly the next bishop, is traditionally said to be a disciple of Nicasius.
Cultus
Nicasius is a saint, listed in the Roman Martyrology on 11 October, his feast day. He is represented in art as a cephalophore, referring to his martyrdom, and as a bishop.