The Oklahoma Land Rush began as thousands of homesteaders staked claims.

1915

The first full-scale use of deadly chemicals in warfare took place as German forces unleashed chlorine gas against Allied troops at the start of the Second Battle of Ypres in Belgium during World War I.

1970

Millions in U.S. concerned about the environment observed the first “Earth Day.”

2012

The U.S. and Afghanistan reached a deal on a strategic partnership agreement ensuring that Americans would provide military and financial support to the Afghan people for at least a decade beyond 2014.