This monograph explores the history of the contribution to ballistics by the American mathematician Gilbert Ames Bliss during World War I. Drawing on the then-evolving calculus of variations, Bliss pioneered a novel technique for solving the problem of differential variations in ballistic trajectory. Called Bliss’ adjoint method, this technique was both hailed and criticized at the time: it was seen as both a triumphant application of pure mathematics to an applied problem and as a complex...