Einstein didn't discover e=mc^2, it was already there.  Maxwell's equations implicitly contain the formula E = mc2. Simon Newcomb pioneered the concept of relativistic energy in 1889.224 Preston, J.J. Thompson,225 Poincare,226 Olinto De Pretto,227 Fritz Hasenohrl,228 [etc. etc. etc.] each effectively (Albert Einstein, himself, did not expressly state it in 1905), or directly, presented the formula E = mc2, before 1905, and Max Planck229 refined the concept in 1906 - 1908, including Newton's230, Bessel's231 and Eotvos'232 implications that inertial mass and gravitational mass are equivalent -- before Albert Einstein.

Ref: http://home.comcast.net/~xtxinc/emc2.htm