Sentence:  But though the Southern States , when drafting a constitution to unite themselves , narrowed the difference to this fine point by omitting to assert the right to secede , the fact remained that by seceding from the Union they had already <WSD>acted</WSD> on the concept that it was composed primarily of sovereign states . 
Meaning of the word marked with <WSD> tags:  regulate one's behavior in accordance with certain information, ideas, or advice