Military temper

The kind of joy and sense of fulfillment people get when thrown together to manage the challenges of some disaster are not unlike the sense of fellowship and belonging soldiers feel in battle when they are part of an army dedicating themselves to the fulfillment of a higher cause. 

That sort of loss of self conjoined with a simultaneous discovery of a higher, greater self is likely what the Chumash means with the word 'tzvaot.' 

"The martial type of character can be bred without war ... The only thing needed henceforward is to inflame the civic temper as past history has inflamed the military temper." (Quoting William James in A Paradise Built In Hell, Rebecca Solnit, 2009; page 53.) 

The Chumash's mode of inflaming the civic temper is the imposition of a national sabbatical year. In James' terms, sheviit would be the moral equivalent of war.