First Appearance: Captain America #71 (March 1949) (sorta--see
Appearances: Captain America #71, Marvel Premiere #30, What If v1 #4, Captain America #285, She-Hulk v2 #22, Thunderbolts #40, , Citizen V & the V-Battalion v1 #1-3, v2 #1-3.
Years Active: 1945-present.
Bucky II was the middle owner of the title in the long line of distinguished Buckys, a lineage that stretches from Atlantis to the modern day, which...okay, maybe not. Bucky II was a child named Fred Davis. When, in 1945, Captain America (I) and Bucky (I) disappeared, President Truman chose the Spirit of '76 to be the new Captain America, Captain America (II), and selected Fred Davis, a former batboy for the New York Yankees, to be Bucky (II). Davis was no stranger to either adventure or superheroes, having helped Bucky (I) to form form the Liberty Legion.
Bucky (II) became a member of the Invaders and worked against the Japanese during the war. After the war Bucky (II) became a member of All-Winners Squad, and fought crime by their side. When Captain America (II) was killed in combat and replaced with Captain America (III), Bucky (II) became his sidekick. Bucky (II) was shot and wounded in 1949, forcing him to retire from crimefighting. Davis appeared in Thunderbolts #40 as a member of the V-Battalion; in the pages of Thunderbolts and Citizen V it was revealed that Davis was a founding member of the V-Battalion's Penance Council, and had been active with them since their establishment.
Bucky (II) had no powers but was athletic and a good fighter. Per Fabian Nicieza, the author of Thunderbolts and Citizen V, Fred Davis' use of a cane in Citizen V and his abandonment of active duty was in fact due to the injury he sustained when he was shot in 1949.
Note: In real life the Golden Girl (I) replaced Bucky (I) as Captain America (I)'s sidekick, beginning with Captain America Comics #66. Interestingly, however, a Bucky appeared in Captain America Comics #71 as Cap's sidekick. That Bucky was gone by issue #72, however. My theory is that the Bucky who appeared in Captain America Comics #71 was Bucky (II), rather than Bucky (I), which is why I have that issue listed as Fred Davis' debut as Bucky (II).