Brief History: The WSM started in 1855 as a Territorial Militia, but by the time we made statehood in 1889, the concept was almost abandoned. It is unclear what exaclty happened, but it appears to be the aftermath of the American Civil War.
I believe from my studies that the U.S. Federal Government tried to step up their power against the Southern States going into the 1860's. Without going into it in depth, communication broke down between the Feds and the States and the Southern States claimed the Feds to be Tyrants. Maybe the South didn't, but I think they did try to use the Constitution of the United States in their defense and were denied. As a result of the breakdown in communications and the Southern States threatened, rebellion began to break out. To supress the rebellion, Abraham Lincoln mobolized the Militias of the States. This decision ended up creating the Confederate States of America and the Southern Army, Navy, and Marine Corps. This was a revolution to the South, but a Civil War to the North. Four years later with over 600,000 dead and 400,000 wounded, the North (Federal Government) supressed the rebellion.
It appears the aftermath of the American Civil War, was the 2nd Amendment Militia suppressed and all the State Militias were to be brought under Federal Government control in the Reconstruction Era from 1863 to 1877. The Washington Territory tried to get statehood in 1878, but it was denied. In 1889, with a Republican in the White House, Washington became a state. However, they lost their 2nd Amendment Militia and it appears they were working on storing all Washingtonians firearms in state armories instead of private dwellings.
Some historians will argue that the States never gave up their power of the Militias to the Feds, and it was all a transition to a new program that worked, because the Militia structure failed and people thought it was a burden. However, the fact the Militia turned into the National Guard is not only unconstitutional, but it shows there was an obvious conspiracy against the people of the United States of Ameica. America was set up to give the People full control of our government with the States having more power then the Federal Government. After the American Civil War, the Federal Government ended up with full control of government and the establishment their Shadow Government with that control, the States became submissive to the Federal Government and the People became Subjects.
Not knowing when and why the WSM went into decline and was disbanded in the 1800's, by 1889 it was something else. From 1889 to 1917, the Militia went into a transition into the National Guard, where it became the reserve component of the Army and then the Air Force like it is today. It's kinda sad what use to be all men from around 15 - 60 years of age was turned into the select few from 18 - 45 years of age and is sent over seas to fight in foreign wars.