The United States choice of Panama for the site of a the canal catalyst for the United States Occupation. President Zelaya was angered by the choice and made negotiations with Germany and Japan for a competing canal in Nicaragua. Once this happened relations with the United States deteriorated, and civil war erupted in 1909 with that 400 United States marines landed on the Caribbean coast.
The United States kept marines in Nicaragua almost continually from 1912 until 1933. Under United States supervision, national elections were held in 1913, but the liberals refused to participate in the electoral process. Foreign investment decreased during this period because of the high levels of violence and political instability.
A conservative, Carlos Solórzano, was elected president in open elections in 1924. After taking office in 1925, Solórzano requested that the United States delay the withdrawal of its troops from Nicaragua. Nicaragua and the United States agreed that United States troops would remain while United States military instructors helped build a national military force. In June, Solórzano’s government contracted with retired United States Army Major Calvin B. Carter to establish and train the National Guard. The United States marines left Nicaragua in August 1925. However, President Solórzano, who had already purged the liberals from his coalition government, was subsequently forced out of power in November 1925 by a conservative group who proclaimed General Emiliano Chamorro as president in January 1926.
Fearing a new round of violence and worried that a revolution in Nicaragua, the United States sent marines, who landed on the Caribbean coast in May 1926, to protect United States citizens and property.
A rebel liberal Augusto César Sandino organized his own army, consisting mostly of peasants and workers, and joined the liberals fighting against the conservative regime of Chamorro. Sandino staged an independent guerrilla campaign against the government and United States forces.
In 1932 Sacasa won the elections and was installed as president in 1933. Anxious to withdraw from Nicaraguan politics, the United States turned over command of the National Guard to the Nicaraguan government. President Sacasa appointed Somoza García as chief director of the National Guard. Somoza García also enjoyed support from the United States government because of his participation at the 1927 peace conference as one of Stimson’s interpreters.
True to his promise to stop fighting after United States marines had left, Sandino agreed to discussions with Sacasa. In 1934, while leaving the presidential palace, Sandino was arrested by National Guard officers acting under Somoza García’s instructions. After Sandino’s execution, the National Guard launched a ruthless campaign against Sandino’s supporters.
Early in 1936, Somoza García openly confronted President Sacasa by using military force to displace local government officials loyal to the president and replacing them with close associates. Somoza García’s increasing military confrontation led to Sacasa’s resignation in 1936. On January 1, 1937, Somoza García resumed control of the National Guard, combining the roles of president and chief director of the military.