Birmingham's alternate history novels resemble those of Harry Turtledove, with whom he shares much of his fan base. The Axis of Time trilogy in particular is reminiscent of Turtledove's Worldwar series. Both involve World War II abruptly being interrupted by the unexpected arrival of a large force of military personnel whose equipment derives from technology two or three generations beyond that of the 1940s, but familiar to the reader at time of publication. Both have subplots centering around social changes driven by social pressures stemming from the arrival of the science fiction contingent. Also, both are told by a large, diverse, and fairly loosely related cast of characters who tell the many contingent stories of a whole narrative. This style is also employed by Birmingham in Without