Complex sentence: Lerdo offered an amnesty, which Díaz accepted, but when Lerdo ran for the presidency in 1876, Díaz successfully rebelled under the Plan de Tuxtepec.
Split into simpler sentences: Lerdo offered an amnesty, which Díaz accepted. However, when Lerdo ran for the presidency in 1876, Díaz successfully rebelled under the Plan de Tuxtepec.