Question: What event did the adament supporter of a leading figure of the Mexican Revolution and main leader of the peasant revolution in the state of Morelos witness when he was seven years old?

Context paragraphs:
Ralph Chaplin: Ralph Hosea Chaplin (1887–1961) was an American writer, artist and labor activist.  At the age of seven, he saw a worker shot dead during the Pullman Strike in Chicago, Illinois.  He had moved with his family from Ames, Kansas to Chicago in 1893.  During a time in Mexico he was influenced by hearing of the execution squads established by Porfirio Díaz, and became a supporter of Emiliano Zapata.  On his return, he began work in various union positions, most of which were poorly paid.  Some of Chaplin's early artwork was done for the "International Socialist Review" and other Charles H. Kerr publications.

Emiliano Zapata: Emiliano Zapata Salazar (] ; 8 August 1879 – 10 April 1919) was a leading figure in the Mexican Revolution, the main leader of the peasant revolution in the state of Morelos, and the inspiration of the agrarian movement called "Zapatismo".

Red Battalions: The Red Battalions were the workers who were hired in the Mexican Revolution to fight against the Zapatistas and Pancho Villa's army.  The Mexican Revolution was a civil war that saw various alliances between different class forces pitted against one another for various political reasons; the Red Battalions belonged largely to the Casa del Obrero Mundial, a worker's organization, and were deployed by Carranza in exchange for various rights for workers, to defeat the "peasant counterrevolutionaries" of Zapata and Villa.  They were called the Red Battalions because of their communist membership.

Battle of Cuautla (1911): The Battle of Cuautla was a battle between the forces of Emiliano Zapata and the federal army of the Mexican government that took place in the state of Morelos from May 11–19, 1911, during the Mexican Revolution.  It has been described as the "six of the most terrible days of battle in the whole Revolution".  Eventually, the remains of the defending "Golden Fifth" regiment, the Fifth Cavalry Regiment of the Federal Army, withdrew and Zapata took control of the town.  The "Zapatista" victory convinced Porfirio Díaz to come to terms with Francisco Madero, agree to the Treaty of Ciudad Juárez and resign as president.

La Adelita: "La Adelita" is one of the most famous "corridos" (folk songs) of the "Mexican Revolution" (1910-1920) that has been adapted in various forms.  This particular version of the ballad (which is also shown in the form of a portrait) was inspired by a Durangan woman (whose identity has not been yet established beyond doubt) who joined the Maderista movement (the revolutionary party led by Francisco I. Madero) at an early stage of the Revolution, and supposedly fell in love with Madero, her revolutionary leader.  Consequently, this popular icon became the source that documented the role of women in the Mexican Revolution, and gradually became synonymous with the term "soldadera" or "female soldier" who became a vital force in the revolutionary war efforts due to their participation in the battles against Mexican government forces."

Battle of Ciudad Juárez (1911): The First Battle of Ciudad Juárez took place in April and May 1911 between federal forces loyal to President Porfirio Díaz and rebel forces of Francisco Madero, during the Mexican Revolution.  Pascual Orozco and Pancho Villa commanded Madero's army, which besieged Ciudad Juárez, Chihuahua.  After two days of fighting the city's garrison surrendered and Orozco and Villa took control of the town.  The fall of Ciudad Juárez to Madero, combined with Emiliano Zapata's taking of Cuautla in Morelos, convinced Díaz that he could not hope to defeat the rebels.  As a result, he agreed to the Treaty of Ciudad Juárez, resigned and went into exile in France, thus ending the initial stage of the Mexican Revolution.

Cristero War: The Cristero War or Cristero Rebellion (1926–29), also known as La Cristiada ] , was a widespread struggle in many central-western Mexican states against the secularist, anti-Catholic and anti-clerical policies of the Mexican government.  The rebellion was set off by enactment under President Plutarco Elías Calles of a statute to enforce the anti-clerical articles of the Mexican Constitution of 1917 (also known as the Calles Law).  Calles sought to eliminate the power of the Catholic Church and organizations affiliated with it as an institution, and also suppress popular religious celebration in local communities.  The massive, popular rural uprising was tacitly supported by the Church hierarchy and was aided by urban Catholic support.  US Ambassador Dwight W. Morrow brokered negotiations between the Calles government and the Church.  The government made some concessions, the Church withdrew its support for the Cristero fighters and the conflict ended in 1929.  It can be seen as a major event in the struggle between Church and State dating back to the 19th century with the War of Reform, but it can also be interpreted as the last major peasant uprising in Mexico following the end of the military phase of the Mexican Revolution in 1920.

Manuel San Martin: Manuel San Martin was born in 1881 in Distrito Federal, Mexico.  A Captain in the Mexican Army and notable figure of the Mexican Revolution.  He opposed corruption within the high ranks of his command in order to save the lives of prisoners wrongfully set for execution.  He saved the lives of countless victims of the Mexican Revolution, where more than two (2) million people lost their lives.  He married Concepcion Espinosa and they had ten children together.  He died on March 25, 1965, in Distrito Federal, Mexico, at the age of 84.

Choe Sihyeong: Choe Sihyeong (Korean: 최시형 ) (1827–1898) original name Choe Gyeongsang, was the second leader of the Donghak Peasant Movement during the Joseon Dynasty and Korean Empire era.  He succeeded Choe Je-u after the latter's execution by Joseon authorities in 1864.  He was born in Gyeongju as a member of the local Choe clan.  In Jeonju, Jeolla, he and his followers attempted to revolt against the Joseon authorities in the aftermath of the Donghak Peasant Revolution, but he was caught by the authorities and executed by firing squad.

Battle of Celaya: The Battle of Celaya, 6–15 April 1915, was part of a series of military engagements in the Bajío during the Mexican Revolution between the winners, who had allied against the regime of Gen. Victoriano Huerta (February 1913 to July 1914) and then fought each other for control of Mexico.  The Constitutionalists under Gen. Venustiano Carranza faced off against the Army of the Convention of Aguascalientes.  The Convention allied Francisco "Pancho" Villa and Emiliano Zapata, who in practice remained in his stronghold of Morelos.  The first battle of Celaya was fought April 6–7, 1915, near Celaya in present-day Guanajuato, Mexico.  The second battle of Celaya was fought April 15–16.  These encounters between the Constitutionalist Army led by Gen. Álvaro Obregón, Venustiano Carranza's best general, and the army under the command of Pancho Villa were crucial in determining the outcome of the Mexican Revolution.

Supporting paragraphs: Ralph Chaplin Emiliano Zapata
Answer: a worker shot dead