Abstract-Over a period of about twenty years, Maxwell's determination and unification of the equations of electricity and magnetism evolved from his first paper on the subject in 1855-56, "On Faraday's Lines of Force," to the publication of his Treatise on Electricity and Magnetism in 1873. Notwithstanding the many historical accounts and textbooks devoted to Maxwell's work, I have not been able to find a reasonably concise, yet definitive summary of the fundamentals of exactly what Maxwell did in his Treatise and how he did it. This paper represents my own attempt to provide such a summary.