On this day...

January 7: Christmas (Julian calendar); Victory Day in Cambodia; Flag Day in Italy

• 1558 – Francis, Duke of Guise, retook Calais, England's last continental possession, for France.
• 1610 – Italian astronomer Galileo Galilei made his first observation of the four Galilean moons through his telescope: Ganymede, Callisto, Io and Europa, although he was not able to distinguish the latter two until the following day.
• 1797 – The first official Italian tricolour was adopted by the government of the Cispadane Republic.
• 1979 – The Vietnam People's Army captured the Cambodian capital city Phnom Penh, deposing Pol Pot and the Khmer Rouge, which marked the end of large-scale fighting in the Cambodian–Vietnamese War.
• 1989 – Akihito (pictured), the current Emperor of Japan, took the throne upon the death of his father Hirohito, who became known by the posthumous name Emperor Shōwa.