Complex sentence: In military conflict against the rising Sassanid Empire, there are mixed accounts, though the Sassanid threat was checked; however, when campaigning against Germanic tribes of Germania, Alexander apparently alienated his legions by engaging in diplomacy and bribery, and they assassinated him.
Split into simpler sentences: In military conflict against the rising Sassanid Empire, there are mixed accounts, though the Sassanid threat was checked. However, when campaigning against Germanic tribes of Germania, Alexander apparently alienated his legions by engaging in diplomacy and bribery, and they assassinated him.