TRO´SSULUM a town of Etruria, which, according to a story current among the Romans, was taken by a body of cavalry alone, unsupported by infantry; an exploit thought to be so singular, that the Roman knights were for some time called Trossuli on account of it. (Plin. Nat. 33.2. s. 9; Festus, s. v. Trossuli, p. 367.) No other mention is found of it; and it was probably a small place which had disappeared in the time of the geographers, but Pliny tells us (l. c.) that it was situated 9 miles from Volsinii, on the side towards Rome. It is said that the name was still retained by a place called Trossoor Vado di Trosso, about 2 miles from Monte Fiascone, as late as the 17th century, but all trace of it is now lost. (Holsten. Not. ad Cluver. p. 67; Dennis's Etruria, vol. 1. p. 517.)
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