text: Historian Allan Nevins argued that the newly inaugurated Lincoln made three miscalculations: underestimating the gravity of the crisis, exaggerating the strength of Unionist sentiment in the South, and overlooking Southern Unionist opposition to an invasion.William Tecumseh Sherman talked to Lincoln during inauguration week and was "sadly disappointed" at his failure to realize that "the country was sleeping on a volcano" and that the South was preparing for war.Donald concludes that, "His repeated efforts to avoid collision in the months between inauguration and the firing on Ft.Sumter showed he adhered to his vow not to be the first to shed fraternal blood.But he also vowed not to surrender the forts.The only resolution of these contradictory positions was for the confederates to fire the first shot; they did just that." On April 15, Lincoln called on the states to send a total of 75,000 volunteer troops to recapture forts, protect Washington, and "preserve the Union", which, in his view, remained intact despite the seceding states.This call forced states to choose sides.Virginia seceded and was rewarded with the designation of Richmond as the Confederate capital, despite its exposure to Union lines.North Carolina, Tennessee, and Arkansas followed over the following two months.Secession sentiment was strong in Missouri and Maryland, but did not prevail; Kentucky remained neutral.The Fort Sumter attack rallied Americans north of the Mason-Dixon line to defend the nation.As States sent Union regiments south, on April 19, Baltimore mobs in control of the rail links attacked Union troops who were changing trains.Local leaders' groups later burned critical rail bridges to the capital and the Army responded by arresting local Maryland officials.Lincoln suspended the writ of habeas corpus in an effort to protect the troops trying to reach Washington.John Merryman, one Maryland official hindering the U.S.