Merickson

Not precisely.

Titanic, Ira Hayes, Reuben James aren't particularly activist songs. (Neither is D-Day Dodgers neither Joshua Fit The Battle Of Jericho, which are on the list, but I didn't mention in the OP.)

Songs that relate historic events.

Of course that will include some activist songs. (There are quite a few labour songs I decided against. e.g. Ludlow Massacre.)

The overall theme is that songs are a way of memorializing the past and the people from the past. The official story isn't always completely factually accurate one.
Neither is the song version (c.f. Pretty Boy Floyd.)
But the song is the version that will be remembered. (Was Old King Cole really merry? That's what his fiddlers three said, so that's all we know about him.)