Complex sentence: On the Eastern frontier things went better, even if with alternate success: in 949 the Byzantines conquered Germanicea, repeatedly defeated the enemy armies and in 952 crossed the upper Euphrates.
Split into simpler sentences: On the Eastern frontier things went better, even if with alternate success. In 949 the Byzantines conquered Germanicea, repeatedly defeated the enemy armies, and in 952 they crossed the upper Euphrates.