The year 1946 was the most optimistic year in American history. Not only was Hitler vanquished, but so was the wolf at the door; if you were a young person, or even not so young, you couldn’t remember a time when the country wasn’t threatened by depression and war. Now anything seemed possible.

The single musician who best reflected this ecstatic attitude was clarinetist, saxophonist, singer, and bandleader Woodrow Charles Thomas Herman (1913-87). His complete sessions from this period have just been collated into a definitive box set, “The Complete Columbia Recordings of Woody Herman and his Orchestra & Woodchoppers (1945-47)” (Mosaic MD7-223, available online at www.mosaic.com). It is unquestionably the best jazz reissue this year.

The great Woody Herman “Thundering Herd” of 1944-46, as band maven George Simon christened it, combined catchy riffs, expert ensemble writing, and inspired soloing. The whimsicality of its music is reflected in titles like “Goosey Gander,” “Your Father’s Mustache” and “Apple Honey” (both “I Got Rhythm” variations), and “Wild Root” and “Blowin’ Up a Storm.” Unlike in the recordings of the era, the jazz doesn’t take a backseat when the band plays a pop song or somebody sings. Some of Herman’s vocals may sound a trifle dated, but his balladeering and straight-ahead blues singing has held up remarkably well.

Herman’s singing was his calling card. He began his career as a child vaudevillian, but caught the jazz bug as a youngster. In the 1920s he trod the boards as a song-and-dance-and-clarinet prodigy, and recorded his first vocals and solos as a featured sideman with California territory bandleader Tom Gerun. After a spell with nationally known Isham Jones, Herman assembled a like-minded group of former Ishamites into a modern swing band in 1936.

The first Woody Herman orchestra was billed as “The Band That Played the Blues” – and Woody himself was the bandleader who sang them better than almost anybody. His biggest hit was a winning elaboration of a simple blues theme called “Woodchopper’s Ball” in 1939.

In the middle war years, Herman’s orchestra was perhaps excessively in thrall to Duke Ellington. It was also, quite frankly, a B-level band compared to such headliners as Benny Goodman or Harry James. But when it came into its own, it captured the imagination of a generation of fans like no other of the era – with the possible exception of Herman’s friend and rival Stan Kenton.

The preoccupation with Ellington eventually paid off, in that it helped Herman and his musical director, Ralph Burns, develop a collection of distinctive tonal colors second only to that of the maestro himself. This is especially apparent in Burns’s only notable extended composition, “Summer Sequence,” the last part of which eventually evolved into the song “Early Autumn,” the melody that made a star out of the young tenor saxophonist Stan Getz.

Burns, who played piano for Herman for about two years, wrote the bulk of the orchestrations and was most responsible for the basic sound of the band. The notes to this package, by Loren Schoenberg, do an excellent job of pointing up his achievement.

If the texture was vaguely Ellingtonian, though, the Herd’s other most notable feature came directly from Count Basie. This was its use of dynamics: No other band besides the Herd placed such an emphasis on a dramatic contrast between loud and soft – the juxtaposition of five trumpets blasting with the pianissimo of vibes and guitar. It’s hardly surprising that Neil Hefti, Herman’s other key arranger of the period, became part of the Basie success story a few years later.

The Herd was known for its spectacular soloists. Trombonist Bill Harris had an extravagantly vocalized tone, alternatively mournful and joyful. Tenor saxophonist Flip Phillips was a rare player of both subtle intelligence and rabble-rousing excitement. And its two best trumpeters – the short-lived Sonny Berman and the long-lived Pete Candoli – could rival either Harry James or Dizzy Gillespie in high-note showmanship.

But Mr. Schoenberg also points out the essential role played by drummer Davey Tough. “It’s unbelievable the way he [could] propel a big band,” Herman is quoted as saying of Tough. “This man had more to say as far as rhythm was concerned than anybody I ever worked with – especially in view of the fact that he had a very limited technique. He was a tiny man and yet he played with the power and strength of a guy three times his size.”

Among his other achievements, Woody Herman was the first mainstream leader to embrace the new music not yet known as modern jazz. Where Billy Eckstine and Dizzy Gillespie led out-and-out bebop big bands, Herman’s approach was more personal and idiosyncratic. Burns and Mr. Hefti found ways to bring bebop into the vocabulary of orchestral jazz, just as jazz composers like Andrew Hill and Herbie Hancock later incorporated free jazz elements into written music.

In the hands of the Herd, though, modernism didn’t sound serious or academic. Rather, it expanded the palette of harmonic possibilities and the supersonic rhythm made the band even more fun to listen to, never more so than with Herman’s adaptation of Louis Jordan’s “Caldonia,” which combines rhythm and blues with bebop and traditional big band swing along with the leader’s whimsical falsetto.

Soon Kenton, Claude Thornhill, Boyd Raeburn, Ray McKinley, and even Tex Beneke were looking in that direction. But none of these groups is as well remembered as Herman’s.

The First Herd was succeeded by the more thoroughly modernistic Second Herd, also known as the Four Brothers band and known for the string of great tenor soloists it showcased, including Stan Getz, Zoot Sims, Al Cohn, and Gene Ammons. But Herman’s winning streak didn’t last; he was undone by the economics of the music industry and certain people he put his trust in (most infamously an embezzling business manager who delivered Herman’s tax payments to bookies rather than the IRS).

Happily, we now have the complete output of his greatest orchestra in its greatest years. This was a band both of its time, and one for all time.