Bilingualism in a Germanic language and Latin was especially important in the military for officers in command of units recruited from Germanic-speaking areas. Tacitus observes that Arminius, the Cheruscan officer who later led a disastrously successful rebellion against the Romans, was bilingual. The emperor Julian employed a bilingual Germanic military tribune as a spy. The officers and secretaries who kept the records preserved in the Vindolanda tablets were Batavian, but their Latin contains no hint; the common soldiers of their units, however, may have retained their Germanic speech. Less commonly, Latin-speaking officers learned a Germanic language through their service and acted as interpreters. Acquiring Germanic might be regarded as a dubious achievement inducing anxieties of "barbarism": in 5th-century Gaul, Sidonius Apollinaris thinks it funny that his learned friend Syagrius has become fluent in Germanic.