"If the Army were one of its own soldiers, the Signal Corps would be his hand in the act of writing, his larynx, palate and tongue in the act of speaking, the ears hearing, and the surface of the skin registering impressions from external invisible energy. It would signal he was about to communicate, it would provide the means for him to do so, and it would enable him to receive the messages of others. Thus in communications the Signal Corps had a notably single mission. Yet almost infinite possibility for variety made it also as complex as the processes of hearing and speaking are. Moreover, like these processes, it was vital. To be able to communicate — to signal — is to be alive." — Dulany Terrett, The Signal Corps: the Emergency  

"Keeping the Army alive throughout World War II was something the Signal Corps did ably. Going from a small, poorly equipped and trained body to a vast organization of skilled soldiers capable of providing global communications systems, the corps' technological achievements were phenomenal.

Yet those achievements only partially explain the branch's contributions to the war effort. Men and women, generals, noncomms and privates were the heart and soul of the World War II Signal Corps. Chief Signal Officer MG Dawson Olmstead presided over a multibillion-dollar budget. MG Spencer Akin managed information in the Pacific theater of war. 1SG Percy Ricks and Women's Army Corps Pvt. Selene Treacy Weise blazed the trail for African-Americans and women in the Signal Corps. 

...our nation changed, both during the war and after. Communications we take for granted as part of the information superhighway strengthened from their World War II use. Wireless communications produced "startling change" in that era, and still do today as the Signal Corps advances in technological capability."

From: Army Communicator, Voice of the Signal Regiment: Introduction