According to Livy's Periochae, the beginning of the consular year changed from March to January1 in 154BC to respond to a rebellion in Hispania. Plutarch believed Numa was responsible for placing January and February first in the calendar; Ovid states January began as the first month and February the last, with its present order owing to the Decemvirs. W. Warde Fowler believed the Roman priests continued to treat January and February as the last months of the calendar throughout the Republican period.