ARQUEBUS, also called HARQUEBUS, HACKBUT, etc., a fire arm of the 16th century, the immediate predecessor of the musket. The word itself is certainly to be derived from the German Hakenbuhse (mod. Hakenbiichse, cf. Eng. hackbut and hackbush), "hook gun." The French arquebuse and Italian arcobugio, archi bugio, often and wrongly supposed to indicate the hackbut's af finity with the crossbow ("hollow bow" or "mouthed bow"), are popular corruptions, the Italian being apparently the earlier of the two and supplanting the first and purest French form haque but. Previous to the French wars in Italy, hand-gun men and even arbalisters seem to have been called arquebusiers, but in the course of these wars the arquebus or hackbut came into prom inence as a distinct type of weapon. The Spanish arquebusiers, who used it with the greatest effect in the Italian wars, notably at Bicocca (1522) and Pavia (1525), are the originators of modern infantry fire action. Filippo Strozzi made many improvements in the arquebus about 1530, and his weapons were effective up to four and five hundred paces. He also standardized the calibres of the arquebuses of the French army, and from this characteristic feature of the improved weapon arose the English term "caliver." In the latter part of the 16th century (c. 1570) the arquebus began to be displaced by the musket.