by Michael Ackerman
At last August’s Curious Cases series presentation at the Homestead, The King Family of El Monte and Personal Justice, 1855-1865, Paul Spitzzeri briefly recounted the lynching of four Latino men following the killing of Sheriff James Barton and a three-man posse, though he’d given a more detailed account in a previous Curious Cases talk on the Barton massacre.
I’m interested in geolocating historical events, and what caught my attention was one line in an article in the February 7, 1857 issue of the Los Angeles Star purporting to give a “correct statement of facts” in response to the “false account of events” in the Spanish-language newspaper El Clamor Publico. The Star notes:
One of the Mexicans, being closely pressed, and having exhausted all his shots, left his horse and took to the swamp, in the rear of the mill of Mr. Courtney.
The Star article continues with a plausible version of events which El Clamor Publico describes in horrifying detail [the man killed in the “swamp” was Miguel Soto, whose head was cut off and the body left unburied, according to the paper, something denied by the Star], but the mention of Mr. Courtney is what jumped out.
Andrew J. Courtney was the son-in-law of Michael White, who came to California with the Rowland-Workman expedition of 1841. Courtney’s wife, Juana Pabla de Jesus White de Courtney, was granted a patent for what became known as the “Courtney Tract,” as shown in this map from the Los Angeles County website. In the upper-right corner is the dam called “La Presa,” unusual for being one of the few structures from the Mission era which remain today. Above the dam is written “Slack Water” and below the dam is a “Grist Mill.” These features closely match the site of the killing described in the Los Angeles Star article.

The Courtney tract was eventually sold to L.J. Rose, and became the nucleus of the Sunny Slope estate, something of a tourist attraction in the late 1800s. The memoir L. J. Rose of Sunny Slope, 1827-1899 by his son, L. J. Rose, Jr. includes biographical notes on many of the locals (including Andrew Courtney) and a harrowing recounting of the Rose-Baley party’s 1858 attempt to travel to California on a new short route, in which eight members were killed by Mojave warriors as the emigrants prepared to cross the Colorado River. The memoir also mentions an old building on the tract, which may or may not be the mill.
Another map from the county website shows part of the Sunny Slope estate at a later date. On the second page is La Presa, this time showing the dam’s distinctive zigzag shape. The grist mill no longer appears. This map is useful because it identifies many features in historical photographs which may be difficult to place, such as the winery building (long gone) and Orange Ave. (now called Vista Street.)

In Mills of the California Missions, Michael O’Shea writes:
Three different mill sites are attributed to this mission. Due to flooding, San Gabriel Mission was relocated from its original site to an area close to a belt of artesian springs caused by an underground geological dike in an earthquake fault. Needed water was dammed and channeled. At the east end of the fault line, it is thought that the first mill “La Presa” was installed. Little is known about this mill. Likely a horizontal mill like the one at San Antonio de Padua. The mill foundation has been found next to its dam. The dam remains exist today on the grounds of the Sunny Slope Water Company. A sawmill is also believed to have been placed at the same site, but with no evidence today.
O’Shea also describes the two better-known mills. In The Three Mills, Michael Hart (who contributed to O’Shea’s article) and Gene Dryden write:
Once upon a time, between 1816 and 1823, there were three grist mills in the San Gabriel Valley. One was located at the exit from Mill Canyon – El Molino Viejo -, one was adjacent to the San Gabriel Mission – the Chapman Mill, and one was adjacent to the Sunny Slope Dam, near an Indian village and presently the site of a condominium complex.
This is all I’ve found about the third (or should I say first) mission mill, but the Curious Cases talk did add to its story.
Michael Ackerman is a Los Angeles native who enrolled at UC Santa Barbara with the intent of studying physics. Upon concluding that he couldn’t grasp calculus, and after taking their truly wonderful required course in American history, he switched that field of study, and fell in love with doing historical research. He is especially interested in geolocation: finding the location of mystery photographs or historical events based on scant evidence. He remains convinced that there is something wrong with the way math is taught, and is looking for low-risk ways to improve math education.