Thread:Netministrator/@comment-1038387-20131220152611/@comment-220364-20131230162348

Small point for argument's sake: Project M was named and fleshed out after Crisis, but IIRC there was an unnamed, rudimentary form of it used as a backstory for the Commandos all along.

That said, the general rule of thumb with the stuff from c. 1960 through Crisis was that Earth-One was the setting unless: That last one is key here I think. Most of Silver Age WWII characters did meet at some point prior to Crisis. Some of them were tied specifically to Earth-One, which then placed those that weren't specifically tied to Earth-One there as well.
 * The narration boxes stated otherwise;
 * DC came back latter and placed it elsewhere (I believe this is what happened with Earth-12);
 * Continuity, at the time, didn't work (There was a non-time travel, Batman-Rock team up in B&B that is an example of this); or
 * It was from a non-super hero anthology and didn't involve characters that were used in cross over stories.