At the breaking out of the civil war, Maryland was claimed by the rebellious States, and for a long time her position seemed uncertain. Miss Carroll, an intimate friend of Gov. Hicks, and at that time a member of his family, favored the national cause, and by her powerful arguments induced the Governor to remain firm in his opposition to the scheme of secession. Thus, despite the siren wooing of the South, in its plaint of "Maryland, my Maryland." Miss Carroll was the means of preserving her native State to the Union. Although a slave-owner, and a member of that class which so largely proved disloyal, Miss Carroll freed her slaves, and devoted herself throughout the war to the cause of liberty. She replied to the secession speech of Senator Breckenridge, made during the July session of Congress 1861, with such lucid and convincing arguments, that the War Department not only circulated a large edition, but the Government requested her to prepare other papers upon unsettled points. In response she wrote a pamphlet entitled "The War Powers of the Government," published in December, 1861. By the especial request of President Lincoln she also prepared a paper entitled "The Relation of Revolted Citizens to the National Government," which was approved by him, and formed the basis of his subsequent action. In September, 1861, she also prepared a paper on the Constitutional power of the President to make arrests, and to suspend the writ of _habeas corpus_; a subject upon which a great conflict of opinion then existed, even among persons of unquestioned loyalty.