Sentence:  The action of the Commission in allowing or denying any claim under this title shall be final and <WSD>conclusive</WSD> on all questions of law and fact and not subject to review by the Secretary of State or any other official , department , agency , or establishment of the United States or by any court by mandamus or otherwise . 
Meaning of the word marked with <WSD> tags:  forming an end or termination; especially putting an end to doubt or question