To maintain his enlarged military, he debased the Roman currency. Upon his accession he decreased the silver purity of the denarius from 81.5% to 78.5%, although the silver weight actually increased, rising from 2.40 grams to 2.46 grams. Nevertheless, the following year he debased the denarius again because of rising military expenditures. The silver purity decreased from 78.5% to 64.5% – the silver weight dropping from 2.46 grams to 1.98 grams. In 196 he reduced the purity and silver weight of the denarius again, to 54% and 1.82 grams respectively. Severus' currency debasement was the largest since the reign of Nero, compromising the long-term strength of the economy.