It has baffled me for a long time. Growing up an army brat I knew of the other branches. There were four. I knew how they came to exist. Originally there was only two branches Army and Navy. The Air Force branched off of the Army. The Marines branched off from the Navy. The thing is when did the lifeguards become a branch of the military? Never once did I hear them referred to as a branch of the military
I remember as a Navy sailor that I was a bit envious of the Coast Guards working schedule. . Reveille Piped at six on my ship and we would be at quarters at seven. Those Coastie‘s didn’t pipe the reveille whistle untill 9 in the morning. We had this old World War II Coast Guard ship called the basswood that would moore not far from us. From my Machine shop I heard their whistle every day. They had it pretty easy.
I’ve seen them repeatedly insinuated as a DOD branch with the other four. Right up to 911 they were DOT. Then they got swapped to DHS. Never have they been DOD. When did this all start?
Short answer, during war time they come under the Navy. Many of the landing craft driver on D Day were Coasties.