Mexico's President Andrés Manuel López Obrador on May 24 officiated over a ceremony in Torreón, Coahuila, where he issued a formal apology for the 1911 massacre of more than 300 members of the northern city's Chinese community at the hands of revolutionary troops. The president said the objective of the apology was to ensure "that this never, ever happens again." Also on hand was Coahuila Gov. Miguel Ángel Riquelme, who said racist ideas fueled "genocidal killings" during a "convulsive" period of Mexico's history. Also attending the ceremony was Chinese Ambassador Zhu Qingqiao. (Mexico News Daily)

What makes this a particularly sensitive question is the fact that the massacre was carried out by forces officially celebrated as the good guys in the Mexican Revolution. This was reflected in local press coverage, which was especially quick to disassociate Pancho Villa, the great leader of revolutionary forces in the north, from the massacre. 

Torreón's Noticias del Sol de la Laguna quotes a joint statement by historians Fernando Ibarra Favela and Sotomayor Garza, who wrote: "There are those who say it was Pancho Villa who carried out this massacre. It is not true; Pancho Villa was a thousand kilometers away when this situation occurred..." They also stated that many torreonenses (residents of Torreón) came to the defense of the Chinese.

And it is true that while the massacre was taking place, Villa was far to the north, fighting in the Battle of Ciudad Juárez (actually a distance of some 800 kilometers). The Wikipedia page on the Torreón massacre makes no mention of Pancho Villa.  An account on McClatchy says it was "a division of Pancho Villa's army" that took Torreón in May 1911. But this is probably not accurate. Villa would not take command of the famous Division of the North until 1913.

Historian Alan Knight in his exhaustive study, The Mexican Revolution, vols 1 & 2 (University of Nebraska 1990), citing local news accounts of the day, names the revolutionary commander at Torreón in May 1911 as one Jesús Flores, who reportedly said of the city's Chinese once his troops were in control, "It would be best to exterminate them." (Vol. 1, p. 207)

Complicating all this is that there were numerous battles of Torreón over the course of Mexico's long and chaotic revolutionary war. First, revolutionary forces took the city from forces loyal to long-ruling dictator Porfirio Díaz in May 1911 (with little resistance), precipitating the massacre. But what history records as the First Battle of Torreón was in September-October 1913—this time Villa's Divsion of the North taking the city from forces loyal to Gen. Victoriano Huerta, who had come to power in a counter-revolutionary coup d'etat in Mexico City (ousting the first revolutionary president, Francisco Madero). There was a  Second Battle of Torreón in March-April 1914, with Villa's army again taking the city from Huerta's forces, who had regained it.

And, finally, there was a Third Battle of Torreón in late December 1916. This was Villa's last gasp. This time his diminished forces took the city from those of his former ally, the more bourgeois revolutionary leader Venustiano Carranza, who had since turned on him. The carrancistas would ultimately emerge victorious, and establish the modern Mexican state.

However, it can't be denied that Villa also committed atrocities against northern Mexico's Chinese. In fact, biographer Friedrich Katz in The Life & Times of Pancho Villa  (Stanford University 1998) writes that when Villa's forces briefly held Torreón after taking it in the closing days of 1916, there was a second massacre of the city's remnant Chinese community, who were "hunted down and killed." (p. 630)

And a report in El Financiero (admittedly, voice of Mexico's business establishment) blames local followers of the anarchist leader Ricardo Flores Magón for stirring up hatred against the Chinese in Torreón, apparently brandng them "migrantes indeseables." 

An interesting addendum to all this is that there was a contingent of Chinese immigrants in US Gen. John J. Pershing's "Punitive Expedition" against Villa in 1916, as recalled by Chinese American Heroes website. They only received US residency for their service—not citizenship—and they had to agitate to get even that. Many of these veterans later settled in San Antonio, Tex., becoming the nucleus of the city's Chinese community, according to Texas Hill Country. 

Lest we forget, there were many massacres of Chinese immigrants in the United States in the late 19th century, and if none were as deadly as what happened in Torreón (nor carried out by military forces), the collective toll likely numbers in the hundreds. Among the most notorious such eruptions of violence were the Los Angeles Chinese massacre of 1871, the San Francisco pogrom of 1877, the Rock Springs massacre of 1885 in Wyoming, and the Hells Canyon massacre of 1887 in Oregon. None have received any apology from a US president, nor much attention in the history books.  

Finally, we can not fail to note the morally equivocal position of Ambassador Zhu Qingqiao at Torreón, given his own government's current racist persecution of the Uighurs of Xinjiang.