This is a LIST driven article. The headline advertises itself as such. Mentioning Civil War battles in the first paragraph then omitting them from the list on the grounds that the battles were not long campaigns is simply a feeble attempt to talk about some battles, particularly WWI battles, that the readers might not be familiar with.
But omitting Civil War battles from the list makes the article inaccurate.
You didn’t read the article and you rushed in with a comment on it; case closed.
“Mentioning Civil War battles in the first paragraph then omitting them from the list on the grounds that the battles were not long campaigns is simply a feeble attempt to talk about some battles, particularly WWI battles, that the readers might not be familiar with.”
This. Any list of “deadliest battles” in American military history should include several from Lincoln’s War.