The Football War was a brief war fought between El Salvador and Honduras in 1969. Existing tensions between the two countries coincided with rioting during a 1970 FIFA World Cup qualifier. The war began on 14 July 1969, when the Salvadoran military launched an attack against Honduras. The Organization of American States (OAS) negotiated a cease-fire on the night of 18 July (hence "100 Hour War"), which took full effect on 20 July. Salvadoran troops were withdrawn in early August.

Although the nickname "Football War" implies that the conflict was due to a football match, the causes of the war go much deeper. The roots were issues over land reform in Honduras and immigration and demographic problems in El Salvador. Honduras is more than five times the size of neighboring El Salvador, but in 1969 the population of El Salvador (3.7 million) was some 40% higher than that of Honduras (2.6 million).

At the beginning of the 20th century, Salvadorans had begun migrating to Honduras in large numbers. By 1969 more than 300,000 Salvadorans were living in Honduras. These Salvadorans made up 20% of the present population of Honduras.

In Honduras, as in much of Central America, most of the land was owned by large landowners or big corporations. The United Fruit Company owned 10% of the land, making it hard for the average landowner to compete. In 1966 United Fruit banded together with many other large companies to create la Federación Nacional de Agricultores y Ganaderos de Honduras (FENAGH; the National Federation of Farmers and Livestock-Farmers of Honduras). FENAGH was anti-peasantry (against the campesino) as well as anti-Salvadoran. This group put pressure on the Honduran president, Gen. Oswaldo López Arellano, to protect the property rights of wealthy landowners.

In 1962 Honduras successfully enacted a new land reform law. This law was fully enforced by 1967; it gave the central government and municipalities much of the land occupied illegally by Salvadoran immigrants and redistributed it to native-born Hondurans as specified by the Land Reform Law. The land was taken from both immigrant farmers and squatters regardless of their ownership or immigration status claims. This created problems for Salvadorans and Hondurans who were married. Thousands of Salvadoran laborers were expelled from Honduras, including both migrant workers and longer-term settlers. This general rise in tensions ultimately led to a military conflict.