Text: In 1868 the Satsuma and Choshu clans, never a real threat to Tokugawa authority as long as they remained rivals, joined forces to overthrow the shogun and restore the authority of the emperor, the 14-year-old Mitsuhito.
Entailment: Satsuma and Choshu clans joined forces in 1868.
Contradiction: Satsuma and Choshu clans waged war against each other in 1868.