Sentence:  "[...] And true it is that the life of man is in the hands of God; and the state of kingdoms doth also belong to Him, to stay or to <WSD>unstay</WSD> them." All men had clearly foreseen that Edward's death would beget the evils of a disputed succession. 
Meaning of the word marked with <WSD> tags:  To undo the establishment of; disestablish; dissolve; divest.