A return to duty comes when he is appointed to be commodore and sent with a squadron of small craft on a mission to the Baltic Sea, where he must be a diplomat as much as an officer. He foils an assassination attempt on Tsar Alexander I of Russia and is influential in the monarch's decision to resist the French invasion of the Russian Empire. While at the court of the Tsar, it is implied (but not explicitly confirmed) that he is unfaithful to Barbara, dallying with a young Russian noblewoman. He provides invaluable assistance in the siege of Riga, employing his bomb-ketches against the French army, where he meets General Carl von Clausewitz of the Prussian Army.