The Vigla (Greek: Βίγλα, "guard watch", from Latin: vigilia), also known as the Arithmos (Greek: Ἀριθμός, "Number") and in English as the Watch, was one of the elite tagmata of the Byzantine army. It was established in the latter half of the 8th century, and survived until the late 11th century. Along with the Noumeroi regiment, the Vigla formed the guard of the imperial palace in Constantinople, and was responsible for the Byzantine emperor's safety on expeditions.