Complex sentence: Army officer, ambitious son of Princess Anna Mikhaylovna Drubetskaya, childhood friend of Countess Rostova; annoyed by his mother's importunings of Prince Vassily on his behalf.
Split into simpler sentences: Army officer, ambitious son of Princess Anna Mikhaylovna Drubetskaya, childhood friend of Countess Rostova. Annoyed by his mother's importunings of Prince Vassily on his behalf.