1 Day - 2 Countries: Facts

[16th century:]

Philip's successors make no attempt to protect Portuguese sensibilities, attempting to rule from Madrid while raising heavy taxes to pay for Spain's wars. The final straw was the attempt by Philip iv (Filipe iii of Portugal) to conscript Portuguese troops to quell a rising in Catalonia. On December 1, 1640, a small group of conspirators stormed the palace in Lisbon and deposed the governor of Portugal. By popular acclaim and despite personal reluctance, the Duke of Braganca, the senior member of the family which had long been the most powerful in the country, took the throne as João iv.

[Text Source: the Rough Guide to Portugal's History mini-chapter; image source: here]

[20th century:]

Great Union Day (Romanian: Ziua Marii Uniri, also called Unification Day) occurring on December 1, is the national holiday of Romania. It commemorates the assembly of the delegates of ethnic Romanians held in Alba Iulia, which declared the Union of Transylvania with Romania.
This holiday was set after the 1989 Romanian Revolution and it marks the unification of Transylvania, but also of the provinces of Bessarabia and Bukovina with the Romanian Kingdom, in 1918.

[Text Source: the Wiki entry on the topic; image source: here]