How did the slave owners prevent “insurrection” from the slave population?

One way in which the owners prevented insurrection was by allowing the slave to partake in holiday celebrations.

From what I know of the effect of these holidays upon the slave, I believe them to be among the most effective means in the hands of the slaveholder in keeping down the spirit of insurrection. Were the slaveholders at once to abandon this practice, I have not the slightest doubt it would lead to an immediate insurrection among the slaves. These holidays serve as conductors, or safety‐valves, to carry off the rebellious spirit of enslaved humanity. But for these, the slave would be forced up to the wildest desperation; and woe betide the slaveholder, the day he ventures to remove or hinder the operation of those conductors! I warn him that, in such an event, a spirit will go forth in their midst,
more to be dreaded than the most appalling earthquake.