One thing Bill Lockhart mentioned in a posting some time ago is that
Germany did not have a corner on the manganese market--it also came from
Brazil, etc. (thus supplies were not suddenly cut off in WWI). It was
likely a combination of factors including George Miller's posting on tank
furnaces that influenced the switch to selenium over a period or years.
Hopefully Bill's article will clarify (hyuck, hyuck) the situation soon!
Thad Van Bueren