War clouds were now beginning to gather over both North and South, and signs of an approaching conflict were ominously clear in Washington, where slavery sentiments swayed all departments. Clara Barton saw with keen mental vision all the signs of the times, and there was much to worry her, for from the first she was clearly and uncompromisingly on the unpopular side of the disturbing question, and believed with Charles Sumner that "Freedom is national; slavery is sectional." She believed in the Union and she believed in the freedom of the individual. So eager was she to help the government in the coming national crisis that she offered her services as a clerk, to do the work of two dishonest men; for this work she was to receive the salary of one clerk, and pay back into the Treasury that of the other, in order to save all the money possible for an emergency. No deed gives a clearer insight into the character of Clara Barton than that. As it was in the case of the school in Bordentown, so was it now. If public service was the question, she had no thought of self or of money--the point was to achieve the desired end. And now she was nearer the goal of her own personal service to the world than she dreamed.
Fort Sumter was fired on. President Lincoln called for seventy-five thousand troops, and all those who were at the seat of government knew that the hour for sacrifice of men and money had come. Massachusetts responded to the call for troops with four regiments, one of which, the Sixth, set out for Washington at once. As they marched through the streets of Baltimore they were attacked by a furious mob who succeeded in killing four soldiers and wounding many more, but the troopers fought them off as bravely as possible and marched on to the station, where they entrained for Washington, many of them arriving there in a pitiable condition. When they detrained at the national capital they were met by a large number of sympathetic women, among them Clara Barton, who recognized some of her old friends and pupils among those who were limping, or with injured arms, or carried on stretchers, and her heart went out to them in loyalty and pride, for they were giving their services to their country in an hour of need.