He denied the constitutionality of secession , and urged that Fort Sumter be properly reinforced and defended .
Black was perhaps the most influential of President Buchanan 's official advisers too , during the secession crisis .
Black denied the constitutionality of secession , and urged that Fort Sumter be properly reinforced and defended .
Black was perhaps the most influential of President Buchanan 's official advisers too , during the secession crisis .