Charles Ellicott Commentary Isaiah 26:21

"For, behold, Jehovah cometh forth out of his place to punish the inhabitants of the earth for their iniquity: the earth also shall disclose her blood, and shall no more cover her slain." — Isaiah 26:21 (ASV)

The earth also shall disclose her blood. —Literally, her bloods (plural of intensity). The prophet has in his thoughts the reckless destruction of life which characterized the great world-powers of Assyria and Babylon. As in the case of Abel’s blood that cried from the ground (Genesis 4:16), so here the earth first brings to light the blood of those who have been slain, and then the forms of the murdered ones themselves.