The WSS was the first Federal Sharpshooter Regt in the field.

There was a great deal of wrangling in the organization of the Eastern Theater's 1st & 2nd U.S.V.S.S., causing significant delay in their deployment. Much of this was the product of an argument between Col Berdan and the Army over Berdan's desire that his men should be armed with a specially modified version of the Sharps Rifle. While Berdan had begun organizing before Birge (and Fremont) the Western regiment moved forward with great speed. "Birge's Western Sharpshooters" was officially in service on Nov 21 8161. Berdan's 1st U.S.V.S.S. was officially mustered in on Nov 29, 1861.The 2nd U.S.V.S.S. were organized later still.

Birge's men were sent to the field (partially trained and partially equipped) in Dec 1861 [on the orders of MG Henry Halleck]. The WSS campaigned against guerrillas and the secessionist Missouri State Guard in foot deep snow along the route of the strategically vital North Missouri Railroad. They fought their first significant action at the Battle of Mount Zion Church (Hallsville, MO) on Dec 28, 1861. They then played a key roll in General Smith's attack on the Confederate right on Feb 15, 1862 at Fort Donelson. Then on April 6, 1862 (the catastrophic 1st day of Shiloh) the Western Sharpshooters held the extreme Union right (along Tighman Branch [Creek] and out to the Snake Creek Bridge) practically alone.

Berdan's men spent their early days of service in the Washington Defenses. They did not see their first action until April 1862: 1st U.S.V.S.S. "Advance on Yorktown" Apr 1-5, 1862; 2nd U.S.V.S.S. "Bristoe Station, VA" Apr 5-6, 1862.

To give Berdan's men credit, they had received a great deal of very valuable training during that time, and acquitted themselves well when they did take the field. The WSS had received minimum training before going into action and although they proved excellent fighters (playing key rolls in two major battles), at the beginning it appears that they weren't very military. That would come when Col Patrick Burke took command in July 1862 at Corinth, and forged them into a crack regiment.
Yours,
James Sullivan