Question: The Smith and Wesson Model 22 series is a refined commercial version of a U.S. six-shot revolver of .45 ACP caliber adopted by the U.S. Army in 1917 durring what war?
Context: The Smith & Wesson K-38 Combat Masterpiece, Revolver Model 15 is a six-shot double-action revolver, with adjustable open sights, built on the medium-size "K" frame.  It is chambered for the .38 Special cartridge and is fitted with a 4 in barrel, though additional barrel options have been offered at various times during its production.  Originally known as the "K-38 Combat Masterpiece", it was renamed the Model 15 in 1957 when all Smith & Wesson revolvers were given numerical model numbers.  It is a shorter barrel version of the Smith & Wesson Model 14 Target Masterpiece and essentially an adjustable-sight version of the seminal Smith & Wesson Model 10 ("Military and Police") revolver with target shooting features.  The main production run of the Model 15 was from 1949 through 1999.  It was discontinued for approximately a decade until 2011, when a re-tooled version was re-released under S&W's Classics Revolvers line. The Smith & Wesson Model K-38 Target Masterpiece Revolver Model 14 is a six-shot, double-action revolver with adjustable open sights built on the medium-size "K" frame.  It is chambered for the .38 Special cartridge, and most were fitted with a 6 in or 8+3/8 in barrel.  A small batch were made with 4 in barrels, and even fewer were made with 5 in barrels.  First produced in 1947 and originally known as the K-38 Target Masterpiece, it was renamed the Model 14 in 1957 when all Smith & Wesson revolvers were given numerical model numbers.  It is built on the same medium-sized frame (K-frame) as the seminal Smith & Wesson Model 10 ("Military and Police") revolver.  The K-38 model was authorized for duty with the Los Angeles Police Department in the 1960s and early 1970s. The M1917 Revolver (formally United States Revolver, Caliber .45, M1917) was a U.S. six-shot revolver of .45 ACP caliber.  It was adopted by the U.S. Army in 1917 to supplement the standard M1911 .45 ACP semi-automatic pistol during World War I. Afterwards, it was primarily used by secondary and non-deployed troops.  There were two variations of the M1917, one made by Colt and the other made by Smith & Wesson. The Smith & Wesson (S&W) Model 625, is a six-round single- and double-action revolver chambered for the .45 ACP (also known as .45 Auto) cartridge and .45 Auto Rim.  The 625 in .45 ACP will headspace the cartridge in the chambers without use of moon clips, but since the extractor cannot engage the rimless cartridge, moon clips are needed to facilitate ejection.  Based on S&W's stainless steel N (large) revolver frame, the Model 625, was introduced as the .45 CAL MODEL OF 1988, in 1988 as a limited edition model intended as an International Practical Shooting Confederation (IPSC) commemorative.  It was equipped with a 5-inch (127 mm) barrel with a full-length underlug. The Smith & Wesson Model 1 1/2 was Smith & Wesson's second .32 caliber revolver, intended to combine the small size and convenience of the Smith & Wesson Model 1 .22 rimfire with the larger caliber of the 6-shot "belt sized" Model 2, which was introduced in 1860.  Chambered in .32 Rimfire, its cylinder held 5 shots.  It was produced in three varieties from 1865 through 1892, with total production exceeding 223,000. The Smith & Wesson Model No. 2 Army a.k.a. "Model No. 2 Old Model Smith & Wesson Revolver" was Smith & Wesson's first .32 caliber revolver, intended to combine the small size and convenience of the Smith & Wesson Model 1 .22 rimfire with a larger caliber.  Chambered in the .32 rimfire long caliber, its cylinder held 6 shots.  It was manufactured 1861 - 1874, with a total production of 77,020. The Colt New Service is a double-action revolver made by Colt from 1898 until 1941.  It was adopted by the U.S. Armed Forces in .45 caliber as the Model 1909 U.S. Army, Marine Corps Model 1909, Model 1909 U.S. Navy and in .45 ACP as the Model 1917 U.S. Army.  The Model 1917 was created to supplement insufficient stocks of M1911 pistols during World War I. The Smith & Wesson Model 10, previously known as the Smith & Wesson .38 Hand Ejector Model of 1899, the Smith & Wesson Military & Police or the Smith & Wesson Victory Model, is a revolver of worldwide popularity.  It was the successor to the Smith & Wesson .32 Hand Ejector Model of 1896 and was the first Smith & Wesson revolver to feature a cylinder release latch on the left side of the frame like the Colt M1889.  In production since 1899, it is a six-shot double-action revolver with fixed sights.  Over its long production run it has been available with barrel lengths of 2 in (51 mm), 3 in (76 mm), 4 in (100 mm), 5 in (130 mm), and 6 in (150 mm).  Barrels of 2.5 inches (64 mm) are also known to have been made for special contracts.  Some 6,000,000 of the type have been produced over the years, making it the most popular centerfire revolver of the 20th century. The Smith & Wesson Model 22 series of revolvers is a refined, commercial version of the M1917 revolver issued during World War I. Evolved from the Smith & Wesson Hand Ejector Model of 1902, the .38 Smith & Wesson Model Military & Police Model of 1905 is the third evolution of the S&W Model 10 (1948 to date) and the forerunner of the S&W Victory revolver.  A six-shot hand-ejector swing-out cylinder) K-Frame revolver chambered in .38 Special (aka 38 S&W Special & 38 Colt Special) with either round-butt or square-butt and checkered walnut or hard rubber grips.  Some models may also have a lanyard "D" ring on the grip butt.  Blue or nickel finish, barrel length 2", 4", 5", 6", or 6.5".  Four-screw cover plate, S&W logo on right side.
Answer: World War I