Preminger, Lubitsch - A Royal Scandal (1945)

In 18th century Russia, a naive and idealistic lieutenant, Alexei Chernoff, deserts his unit and rushes to the Imperial Palace to warn Empress Catherine the Great of great dangers. Lieutenant Chernoff's fiancee, Countess Anna, is one of the ladies-in-waiting of the Empress. Upon forcing his way into the palace, lieutenant Chernoff meets Chancellor Nicolai Iiyitch who promises to convey his warning to the Empress but Chernoff wants to meet the Empress in person. His fiancee is also surprised to see Chernoff inside the palace. After Chernoff finally meets the Empress, he's mesmerized by her personality and swears to give his life to protect her. Catherine is impressed by his sense of sacrifice, innocence, sincerity, loyalty and also by his good looks. Infatuated with him, she makes him her boy-toy, to Anna's dismay. Overnight, Chernoff is appointed Chief of the Imperial Guard and his rank is raised to captain, to major, or to colonel, according to Empress Catherine's romantic mood.