United States interest in Nicaragua, which had waned during the last half of the 1800s because of isolationist sentiment following the United States Civil War (1861-65), grew again during the final years of the Zelaya administration. Angered by the United States choice of Panama for the site of a transisthmian canal, President Zelaya made concessions to Germany and Japan for a competing canal across Nicaragua. Relations with the United States deteriorated, and civil war erupted in October 1909, when anti-Zelaya liberals joined with a group of conservatives under Juan Estrada to overthrow the government. The United States broke diplomatic relations with the Zelaya administration after two United States mercenaries serving with the rebels were captured and executed by government forces. Soon thereafter, 400 United States marines landed on the Caribbean coast. Weakened and pressured by both domestic and external forces, Zelaya resigned on December 17, 1909. His minister of foreign affairs, José Madriz, was appointed president by the Nicaraguan Congress. A liberal from León, Madriz was unable to restore order under continuing pressure from conservatives and the United States forces, and he resigned on August 20, 1910.

Conservative Estrada, governor of Nicaragua's easternmost department, assumed power after Madriz's resignation. The United States agreed to support Estrada, provided that a Constituent Assembly was elected to write a constitution. After agreeing with this stipulation, a coalition conservative-liberal regime, headed by Estrada, was recognized by the United States on January 1, 1911. Political differences between the two parties soon surfaced, however, and minister of war General Luis Mena forced Estrada to resign. Estrada's vice president, the conservative Adolfo Díaz, then became president. In mid-1912 Mena persuaded a Constituent Assembly to name him successor to Díaz when Díaz's term expired in 1913. When the United States refused to recognize the Constituent Assembly's decision, Mena rebelled against the Díaz government. A force led by liberal Benjamín Zelaydón quickly came to the aid of Mena. Díaz, relying on what was becoming a time-honored tradition, requested assistance from the United States. In August 1912, a force of 2,700 United States marines once landed again at the ports of Corinto and Bluefields. Mena fled the country, and Zelaydón was killed.

The United States kept a contingent force in Nicaragua almost continually from 1912 until 1933. Although reduced to 100 in 1913, the contingent served as a reminder of the willingness of the United States to use force and its desire to keep conservative governments in power. Under United States supervision, national elections were held in 1913, but the liberals refused to participate in the electoral process, and Adolfo Díaz was reelected to a full term. Foreign investment decreased during this period because of the high levels of violence and political instability. Nicaragua and the United States signed but never ratified the Castill-Knox Treaty in 1914, giving the United States the right to int 2000 tervene in Nicaragua to protect United States interest. A modified version, the Chamorro- Bryan Treaty omitting the intervention clause, was finally ratified by the United States Senate in 1916. This treaty gave the United States exclusive rights to build an interoceanic canal across Nicaragua. Because the United States had already built the Panama Canal, however, the terms of the Chamorro-Bryan Treaty served the primary purpose of securing United States interests against potential foreign countries--mainly Germany or Japan--building another canal in Central America. The treaty also transformed Nicaragua into a near United States protectorate.

Collaboration with the United States allowed the conservatives to remain in power until 1925. The liberals boycotted the 1916 election, and conservative Emiliano Chamorro was elected with no opposition. The liberals did participate in the 1920 elections, but the backing of the United States and a fraudulent election assured the election of Emiliano Chamorro's uncle, Diego Manuel Chamorro.

A moderate conservative, Carlos Solórzano, was elected president in open elections in 1924, with liberal Juan Bautista Sacasa as his vice president. After taking office on January 1, 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 (who had also served as president from 1917 to 1921), as president in January 1926.

Fearing a new round of conservative-liberal violence and worried that a revolution in Nicaragua might result in a leftist victory as happened a few years earlier in Mexico, the United States sent marines, who landed on the Caribbean coast in May 1926, ostensibly to protect United States citizens and property. United States authorities in Nicaragua mediated a peace agreement between the liberals and the conservatives in October 1926. Chamorro resigned, and the Nicaraguan Congress elected Adolfo Díaz as president (Díaz had previously served as president, 1911- 16). Violence resumed, however, when former vice president Sacasa returned from exile to claim his rights to the presidency. In April 1927, the United States sent Henry L. Stimson to mediate the civil war. Once in Nicaragua, Stimson began conversations with President Díaz as well as with leaders from both political parties. Stimson's meetings with General José María Moncada, the leader of the liberal rebels, led to a peaceful solution of the crisis. On May 20, 1927, Moncada agreed to a plan in which both sides--the government and Moncada's liberal forces--would disarm. In addition, a nonpartisan military force would be established under United States supervision. This accord was known as the Pact of Espino Negro.

As part of the agreement, President Díaz would finish his term and United States forces would remain in Nicaragua to maintain order and supervise the 1928 elections. A truce between the government and the rebels remained in effect and included the disarmament of both liberal rebels and government troops. Sacasa, who refused to sign the agreement, left the country. United States forces took over the country's military functions, and strengthened the Nicaraguan National Guard.

A rebel liberal group under the leadership of Augusto César Sandino also refused to sign the Pact of Espino Negro. An illegitimate son of a wealthy landowner and a mestizo servant, Sandino had left his father's home early in his youth and traveled to Honduras, Guatemala, and Mexico. During his three-year stay in Tampico, Mexico, Sandino had acquired a strong sense of Nicaraguan nationalism and pride in his mestizo heritage. At the urging of his father, Sandino had returned to Nicaragua in 1926 and settled in the department of Nueva Segovia, where he worked at a gold mine owned by a United States company. Sandino, who lectured the mine workers about social inequalities and the need to change the political system, soon organized his own army, consisting mostly of peasants and workers, and joined the liberals fighting against the conservative regime of Chamorro. Highly distrusted by Moncada, Sandino set up hit-and-run operations against conservative forces independently of Moncada's liberal army. After the United States mediated the agreement between liberal forces and the conservative regime, Sandino, calling Moncada a traitor and denouncing United States intervention, reorganized his forces as the Army for the Defense of Nicaraguan Sovereignty (Ejército Defensor de la Soberanía de Nicaragua-EDSN). Sandino then staged an independent guerrilla campaign against the government and United States forces. Although Sandino's original intentions were to restore constitutional government under Sacasa, after the Pact of Espino Negro agreement his objective became the defense of Nicaraguan sovereignty against the United States. Receiving his main support from the rural population, Sandino resumed his battle against United States troops. At the height of his guerrilla campaign, Sandino claimed to have some 3,000 soldiers in his army, although official figures estimated the number at only 300. Sandino's guerrilla war caused significant damage in the Caribbean coast and mining regions. After debating whether to continue direct fighting against Sandino's forces, the United States opted to develop the nonpartisan Nicaraguan National Guard to contain internal violence. The National Guard would soon become the most important power in Nicaraguan politics.

The late 1920s and early 1930s saw the growing power of Anastasio "Tacho" Somoza García, a leader who would create a dynasty that ruled Nicaragua for four and a half decades. Moncada won the 1928 presidential elections in one of the most honest elections ever held in Nicaragua. For the 1932 elections, the liberals nominated Juan Bautista Sacasa and the conservatives, Adolfo Díaz. Sacasa won the elections and was installed as president on January 2, 1933. In the United States, popular opposition to the Nicaraguan intervention rose as United States casualty lists grew. Anxious to withdraw from Nicaraguan politics, the United States turned over command of the National Guard to the Nicaraguan government, and United States marines left the country soon thereafter. President Sacasa, under pressure from General Moncada, appointed Somoza García as chief director of the National Guard. Somoza García, a close friend of Moncada and nephew of President Sacasa, had supported the liberal revolt in 1926. 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. Having attended school in Philadelphia and been trained by United States marines, Somoza García, who was fluent in English, had developed friends with military, economic, and political influence in the United States.

After United States troops left Nicaragua in January 1933, the Sacasa government and the National Guard still were threatened by Sandino's EDSN. True to his promise to stop fighting after United States marines had left the country, Sandino agreed to discussions with Sacasa. In February 1934, these negotiations began. During their meetings, Sacasa offered Sandino a general amnesty as well as land and safeguards for him and his guerrilla forces. However, Sandino, who regarded the National Guard as unconstitutional because of its ties to the United States military, insisted on the guard's dissolution. His attitude made him very unpopular with Somoza Garcia and his guards. Without consulting the president, Somoza Garcia gave orders for Sandino's assassinatcaf ation, hoping that this action would help him win the loyalty of senior guard officers. On February 21, 1934, while leaving the presidential palace after a dinner with President Sacasa, Sandino and two of his generals were arrested by National Guard officers acting under Somoza García's instructions. They were then taken to the airfield, executed, and buried in unmarked graves. Despite Sacasa's strong disapproval of Somoza García's action, the Nicaraguan president was too weak to contain the National Guard director. After Sandino's execution, the National Guard launched a ruthless campaign against Sandino's supporters. In less than a month, Sandino's army was totally destroyed.

President Sacasa's popularity decreased as a result of his poor leadership and accusations of fraud in the 1934 congressional elections. Somoza García benefited from Sacasa's diminishing power, while at the same time he brought together the National Guard and the Liberal Party (Partido Liberal-PL) in order to win the presidential elections in 1936. Somoza García also cultivated support from former presidents Moncada and Chamorro while consolidating control within the Liberal Party.

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 on June 6, 1936. The Congress appointed Carlos Brenes Jarquín, a Somoza García associate, as interim president and postponed presidential elections until December. In November, Somoza García officially resigned as chief director of the National Guard, thus complying with constitutional requirements for eligibility to run for the presidency. The Liberal Nationalist Party (Partido Liberal Nacionalista--PLN) was established with support from a faction of the Conservative Party to support Somoza García's candidacy. Somoza García was elected president in the December election by the remarkable margin of 107,201 votes to 108. On January 1, 1937, Somoza García resumed control of the National Guard, combining the roles of president and chief director of the military. Thus, Somoza García established a military dictatorship, in the shadows of democratic laws, that would last more than four decades.

Data as of December 1993