Complex sentence: But he had left this campaign too late in the year and when the wintry season came on early in the Armenian Tablelands, frustrated by the rough terrain of Northern Armenia and seeing the worsening morale of his troops, Lucullus moved back south.
Split into simpler sentences: But he had left this campaign too late in the year and when the wintry season came on early in the Armenian Tablelands. Frustrated by the rough terrain of Northern Armenia and seeing the worsening moral of his troops, Lucullus moved back south.