sentences:  When the Civil War began in April 1861, there were only about 16,000 men in the U.S. Army, and many Southern soldiers and officers were already resigning and joining the new Confederate States Army.With this drastic shortage of men in the army, President Abraham Lincoln called on the states to raise a force of 75,000 volunteers for three months to put down the insurrection in the South.Accordingly, the 1st Delaware Infantry Regiment was raised at Wilmington, Delaware, on May 22, 1861, and mustered into Federal service on May 28.