Кунашир
In 1811, Vasily Golovnin, a Russian explorer tasked by Tsar Alexander I with mapping the Kuril Islands, was captured by the Japanese. When Golovnin and his crew aboard the ship "Diana" approached Kunashir Island, they were taken ashore and imprisoned for violating Sakoku, or Japanese isolationist policies. Golovnin and his crew were held prisoner for two years and were released in 1813. This event, known as the Golovnin Incident, demonstrated that the border between Russia and Japan was too vague for the Russian Empire, and that to avoid another episode such as Golovnin's, the border needed to be clearly defined.