The Battle of Bear Valley was a small engagement fought in 1918 between a band of Yaquis and a detachment of United States Army soldiers.

On January 9, 1918, elements of the American 10th Cavalry Regiment of Buffalo Soldiers detected about thirty armed Yaquis in Bear Valley, west of Nogales, Arizona, a large area that was commonly used as a passage across the international border with Mexico.

The fact that Yaquis were buying arms in Arizona and smuggling them across the border became so well known that the military governor of Sonora, General Plutarco Elías Calles, informally requested help from the United States government in dealing with the problem.

Furthermore, Arizona ranchers began reporting in larger numbers their encounters with armed Yaquis on their ranch land or the finding of butchered livestock on the range.

The Nogales, Arizona subdistrict commander, Colonel J.C. Friers, 35th Infantry, responded to the reports by issuing orders to increase patrolling in the area.

American forces in the area included the 35th Infantry Regiment, stationed at Camp Stephen D. Little in Nogales, and the 10th Cavalry Buffalo Soldiers, who were spread out to protect the various towns near the international border.

Smaller posts were also established at Arivaca and Oro Blanco and, finally, a troop of about thirty men maintained a camp at Atascosa Canyon, a "strategic natural crossing" within Bear Valley.

[1] On January 8, a local cattleman and owner of the Ruby Mercantile, Philip C. Clarke, rode into camp and told Captain Ryder that his neighbor found the body of a cow in the mountains to the north and that a piece of its hide had been removed for making sandals.

It was assumed that Yaquis killed the cow so Ryder strengthened the observation post on top of the ridge by sending up First Lieutenant William Scott and a detail of men equipped with field glasses to watch the trails from a distance.

By the time the soldiers left camp the Yaquis were no longer in sight but Lieutenant Scott kept pointing so the troop kept moving due south, towards the border fence.

When the Americans were finally in position, they dismounted in a "shallow brushy draw," left a guard to watch the horses, and then continued advancing on foot in a skirmish line.

Moving forward, the soldiers were nearing the top of a canyon side when Captain Ryder decided to return to the horses, using a different path.

Wharfield wrote that "the fighting developed into an old kind of Indian engagement with both sides using all the natural cover of boulders and brush to full advantage.

"[1] Captain Ryder wrote Colonel Wharfield the following for his book: The Cavalry line maintained its forward movement, checked at times by the hostile fire, but constantly keeping contact with the Indians.

I sent some soldiers to try and get an automobile or any transportation at the mining camps [Arivaca, Ruby, Oro Blanco] for the wounded Yaqui, but none could be located until morning.

There were a dozen or more rifles, some .30-30 Winchester carbines and German Mausers, lots of ammunition, powder and lead, and bullet molds.

All ten of the Yaquis, including the boy, volunteered to enlist in the Army but the government had other plans and the prisoners were later sent to Tucson for trial in federal court.

Charged with "wrongfully, unlawfully, and feloniously exporting to Mexico certain arms and ammunition, to wit: 300 rifle cartridges and about 9 rifles without first procuring an export license issued by the War Trade Board of the United States," the Yaquis pleaded guilty and were sentenced by Judge William Henry Sawtelle to a mere thirty days in jail, excluding the boy whose charges were dismissed.