Answer
King Chulalongkorn of Siam and his father King Mongkut observed a solar eclipse in 1868. Chulalongkorn was 15 at the time. The eclipse occurred during the rainy season in Southeast Asia, when mosquitoes carrying malaria are most active. Both King Chulalongkorn and his father contracted malaria from the mosquitoes, and King Mongkut died a few months later.