681    Bulgaria is founded as a Khanate on the south bank of the Danube after defeating the Byzantine armies of Emperor Constantine IV south of the Danube delta.

893    Simeon I of Bulgaria is crowned Emperor of the first Bulgarian empire

1230    Bulgarian tsar Ivan Asen II defeats Theodore of Epirus in the Battle of Klokotnitsa.

1873    Bulgarian revolutionary leader Vasil Levski is executed by hanging in Sofia by the Ottoman authorities.

1876    The April Uprising breaks out in Bulgaria.

1876    Hristo Botev, a national revolutionary of Bulgaria, is killed in Stara Planina

1878    Bulgaria regains its independence from Ottoman Empire according to the Treaty of San Stefano; shortly after Congress of Berlin stripped its status to an autonomous state of the Ottoman Empire.

1885    Eastern Rumelia declares its union with Bulgaria. The Unification of Bulgaria is accomplished.

1908    The independence of Bulgaria is proclaimed.

1912    Bulgaria, Greece and Serbia declare war on the Ottoman Empire, joining Montenegro in the First Balkan War.

1912    During the First Balkan War, Kardzhali is liberated by Bulgarian forces

1912    Bulgaria, Greece, Montenegro, and Serbia (the Balkan League) sign an armistice with Turkey, ending the two-month long First Balkan War.

1913    Balkan War: Bulgarian forces take Adrianople.

1913    Greece and Serbia annul their alliance with Bulgaria.

1913    Second Balkan War: delegates from Bulgaria, Romania, Serbia, Montenegro, and Greece sign the Treaty of Bucharest, ending the war.

1914    Serbia and Bulgaria interrupt diplomatic relationship.

1915    Bulgaria enters World War I as one of the Central Powers.

1918    World War I: The Hindenburg Line is broken by Allied forces. Bulgaria signs an armistice.

1923    Bulgaria's military takes over the government in a coup.

1923    The Treaty of Lausanne, settling the boundaries of modern Turkey, is signed in Switzerland by Greece, Bulgaria and other countries that fought in World War I.

1938    Bulgaria signs a non-aggression pact with Greece and other states of Balkan Antanti (Turkey, Romania, Yugoslavia).

1940    Treaty of Craiova: Romania loses Southern Dobrudja to Bulgaria.

1941    World War II: Bulgaria signs the Tripartite Pact, allying itself with the Axis powers.

1941    World War II: First German military units enter Bulgaria after it joined the Axis Pact.

1941    World War II: UK declares war on Bulgaria. Hungary and Romania declare war on the United States. India declares war on Japan.

1942    World War II: United States declares war on Bulgaria, Hungary, and Romania.

1944    World War II: The Fatherland Front takes power in Bulgaria through a military coup in the capital and armed rebellion in the country. A new pro-Soviet government is established.

1955    Albania, Austria, Bulgaria, Cambodia, Finland, Hungary, Ireland, Italy, Jordan, Laos, Libya, Nepal, Portugal, Romania, Spain and Sri Lanka join the United Nations.

1978    While walking across Waterloo Bridge in London, Bulgarian dissident Georgi Markov is assassinated by Bulgarian secret police agent Francesco Giullino by means of a ricin pellet fired from a specially-designed umbrella.

1978    While walking across Waterloo Bridge in London, Bulgarian dissident Georgi Markov is assassinated by Bulgarian secret police agent Francesco Giullino by means of a ricin pellet fired from a specially-designed umbrella.

1989    Fall of the communist regime in Bulgaria.

1998    While ''en route'' from Adana to Ankara, a Turkish Airlines flight with a crew of 6 and 33 passengers is hijacked by a Kurdish militant who orders the pilot to fly to Switzerland. The plane instead lands in Ankara after the pilot tricked the hijacker into thinking that he is landing in the Bulgarian capital of Sofia to refuel.

2001    Simeon Saxe-Coburg-Gotha, the last Tsar of Bulgaria when he was a child, is sworn in as Prime Minister of Bulgaria, becoming the first monarch in history to regain political power through democratic election to a different office.

2001    Bulgaria, Cyprus, Latvia, Malta, Slovenia and Slovakia join the European Environment Agency.

2002    NATO invites Bulgaria, Estonia, Latvia, Lithuania, Romania, Slovakia and Slovenia to become members.

2004    Bulgaria, Estonia, Latvia, Lithuania, Romania, Slovakia and Slovenia join NATO as full members.

2005    Bulgaria and Romania sign accession treaties to join the European Union.

2007    Bulgaria and Romania officially join the European Union. Also, Bulgarian, Romanian, and Irish become official languages of the European Union, joining 20 other official languages.