Caesar's most remarkable and durable reform at this period was the REVISION OF THE CALENDAR. The Roman method of reckoning time had been so inaccurate, that now their seasons were more than two months behind. Caesar established a calendar, which, with slight changes, is still in use. It went into operation January 1st, 45. He employed Sosigenes, an Alexandrian astronomer, to superintend the reform. While Sosigenes was at work on the calendar, Caesar purified the Senate. Many who were guilty of extortion and corruption were expelled, and the vacancies filled with persons of merit. Meanwhile matters in Spain were not satisfactory. After the battle of Pharsalia, Cassius Longinus, Trebonius, and Marcus Aemilius Lepidus had been sent to govern the province. They could not agree. The soldiers became mutinous. To Spain flocked all who were dissatisfied with Roman affairs. The remnant of Scipio's African army rested there in its wanderings. Thus Labienus and Pompey's two sons managed to collect an army as numerous as that which had been defeated at Thapsus. There were thirteen legions in all. Caesar saw that he must make one more struggle. He set out for the province accompanied by his nephew OCTAVIUS (afterwards the Emperor AUGUSTUS), and by his trusted friend and officer, DECIMUS BRUTUS. The struggle in Spain was protracted for several months, but the decisive battle was fought at MUNDA, 17 March, 45, on the Guadalquivir, near Cordova. The forces were well matched. The advantage in position was on the side of the enemy. The battle was stubbornly fought, most of it hand to hand, with short swords. So equal was the struggle, so doubtful at one time the issue, that Caesar himself sprang from his horse, seized a standard, and rallied a wavering legion. Finally, Labienus was seen to gallop across the field. It was thought he was fleeing. Panic seized his troops, they broke and ran. Thirty thousand were slain, including three thousand Roman Knights, and Labienus himself. Gnaeus Pompey shortly after lost his life, but Sextus lived for a number of years. Caesar tarried in Spain, regulating affairs, until late in the autumn, when he returned to Rome and enjoyed another triumph over the Iberians (Spaniards). The triumph was followed, as usual, by games and festivals, which kept the populace in a fever of delight and admiration. CATO.-METELLUS SCIPIO.