The Spaniards were obliged to appropriate some of the best lands to till for the support of the missions, and this, together with the general poverty of the establishments when he had expected something fine, disgusted Palma and exasperated him and the other Yumas.

In June, 1781, Captain Moncada, lieutenant-governor of Lower California, arrived with soldiers and recruits en route for California settlements, and encamped opposite Yuma.

After some of these people had been sent forward or back as the plans demanded, Moncada remained at the camp with a few of his soldiers.
No one suspected the tornado which was brewing.

All the life of the camp, of the missions, and of the Yumas went on with the same apparent smoothness, but it was only a delusion suddenly and horribly dispelled on the fateful 17th of July.

Without a sign preliminary to the execution of their wrath, Captain Palma and all his band threw piety to the winds, and annihilated with clubs Moncada's camp and most of the men in the two missions.