On June 28, 1914, Serbian assassinated of Austria-Hungary while on a visit to Sarajevo, Serbia.

After Serbia refused a complete investigation, Austria-Hungary, with the backing of its ally , declared war on Serbia. Serbia called on its ally .

Germany viewed the Russian mobilization as an act of war, and declared war on Russia. Germany declared war on , which was allied with Russia by treaty. Germany invaded , a neutral country, so as to be closer to . , bound by treaty to defend both and , declared war on .

The United States, under President , declared and enter World War I immediately.

When threatened commercial shipping with warfare, the United States got involved in .

Fighting of World War I continued until November . Germany petitioned for armistice and the was signed in June of . The was also established which was a group of countries that agreed to avoid conflict through and .

Severely limited by the Treaty of Versailles, grew to resent its terms: reparations and a limited size army.

In 1933, became chancellor of Germany and shortly thereafter was granted powers. He was determined to remove all restrictions on Germany and unify the countries into a country. Hitler marched on in 1938.

Hitler made a claim on , which was supported internationally, but then continued to march into the rest of , to which he had no claim. and pledged to fight Germany if Hitler invaded , which he did in September 1939. and declared war on Germany.

The United States stayed out of World War II until bombed , Hawaii on December , .

The European theater of WWII ended in , when Allied troops invaded and committed suicide. In the Pacific, the U.S. dropped two on and , Japan, forcing them to surrender.

Japan's surrender at the end of WWII ended its 35 year occupation of . The and assumed trusteeship of the country, with the occupying the northern half and controlling the south.

Elections were ordered by the United Nations to establish a unified government in Korea, but the result was the formation of two states divided along the - parallel. Conflicting claims led to occasional skirmishes along the common border throughout 1949 aiming to the country under its own government.

In June 1950, Korea mounted a major attack across the border, marking what is considered the beginning of the Korean War.

For the Korean War the North Koreans received military aid and backing from the . In August 1950, troops arrived in South Korea to join the fight along with the , , and forces.

The Soviet involvement in the Korean War caused the United States to fear the spread of and .

Control of the Korean peninsula was described as a , with North Korea capturing the South Korean capital of and then being pushed back with southern forces eventually capturing the North Korean capital, . This caused the army to join the fight.

In peace negotiations for the Korean War resulted in a cease-fire and created a buffer zone between the two countries. This cease fire is in effect. The Korean War officially ended.

North Korea has become an increasingly isolated , while South Korea has grown into a major .

Vietnam became a divided country after WWII, with a - and -backed communist government in the north, led by , and a -backed government in the south.

The United States became minimally militarily involved with Vietnam and in North Vietnamese forces attacked U.S. in the of . Subsequently, the U.S. sent more and more troops over the next four years.

As fighting continued with no decisive progress, to the war began to grow among the American public. President began reducing the troops while trying to assist the South Vietnamese army in building to fight on its own.

In January 1973, the were signed, ending offensive action by the United States in Vietnam. Nixon promised defensive assistance, but in 1974 cut off funding after Nixon resigned following the .

North Vietnamese forces took , the southern capital, in April . North and South were unified under one government.

During the Vietnam War, opposition to the and to U.S. in the war led to large , particularly among young people. Returning found they were treated as heroes.

The beginning of the modern civil rights movement is defined as the , in 1955. The movement used nonviolence to end segregation in public places.

v. contributed to integrating the South by ruling separate schools for white and black students was unconstitutional.

The of 1965 helped African Americans exercise the rights that the Constitution had guaranteed. In the late 1960s and 1970s, the Civil Rights movement grew to include more radical organizations like the .

In 1957, the formation of the by Martin Luther King, Jr., John , Rev. C.D. , Rev. T.J. , Rev. Fred , Ella , A. Philip , Bayard , and Stanley provided training and assistance to many local efforts to fight segregation.

The major method of fighting segregation and racism for the Southern Christian Leadership Conference was .

The terrorist attack on the United States in 2001 prompted a military invasion of .

Shortly after invading the Middle East, the United States, the UK, and several smaller countries addressed further instability in the region by ousting Iraqi dictator .

In the eastern Mediterranean, tension between and continued to build, regularly erupting into violence.

The threat of the spread of nuclear weapons reared its head again with North Korea's nuclear missile and ongoing suspicion that Iran is working toward the of weapons-grade material.

In , Texans felt the effects of the Great Depression. Unemployment and programs eventually helped return the economy to a more stable level.

In the 1930s, a severe extended across the Panhandle of the state. was blown off the dry lands and storms of dust swept across the region. This resulted in the . Subsequently, Congress passed legislation.

in Texas began to take place rapidly after the discovery of oil. Cities grew up along the , and population moved from to . Towns sprang up along . and grew, even during the Depression.

After World War II ended, became the fastest growing city in the nation. developed as a center of higher education, and grew after serving as a military base during the Second World War.

Contemporary societies upon past historical events to learn form the and of those events to take in future similar events.