The first Roman asses were issued in 289 BC. They were heavy bronze coins, too large and bulky to be minted. They were therefore cast. They were neither especially pretty nor especially handy, but presented the high value of about 270 grams of bronze.
Over the following decades, bronze became more and more valuable in the Roman Empire: Rome waged wars almost incessantly and needed large amounts of bronze for armament. The valorization of the metal made it possible to diminish the bronze coins without reducing their value. Around 211 BC, the as had become so small that it could henceforth be minted.
The coin motifs remained the same. The obverse depicted the bearded head of Janus and the specification of value, I. The reverse showed a prow, the value I again, and the indication of the minting authority ROMA.