http://www.nationmaster.com/encyclopedia/Yom-Kippur-War

The conflict lasted for three weeks in October of 1973. The main participants were Israel, supported by the US, and Egypt and Syria, who were supported by Iraq, Jordan and Saudi Arabia. The EC was slow to join in. The EC's lack of support angered the US and the US's involvement angered the EC...

http://www.bartleby.com/65/vi/VietnamW.html

Conflict between South Vietnam and North Vietnam that lasted from 1954 until 1975. The United States sent troops in to support South Vietnam in 1961. This war caused conflict between the United States and European states. The US was angry at the lack of support from Europe and many European nations openly criticised the US for getting involved. Eventually, world-wide anti-war movements brought the war to an end...