The medieval battle for England’s throne reaches a major turning point in this week’s “War at First Hand,” an intense rollercoaster ride marking the end, and rise to power, of several major characters in the series, The White Queen. Unlike some previous episodes, “War at First Hand” does a better job of balancing the continuity of its characters’ storylines, as well as the dramatic tone of its heavier, atmospheric, battle sequences. This all adds up to a thrilling and compelling episode that suggests more bloodshed in the future.