The bulk update request #14859 has been approved by @evazion.
create alias infantry -> soldier
rename grenadier -> grenadier_(manga)
There's the tag called infantry with only 6 posts. I assume this tag was meant to be used specifically for foot soldier. However, since most of the post with "soldier" tag involves infantry, I think this should be be an alias instead of a separate tag.
Also, there's a tag for the manga called "Grenadier", but it lacks any qualifier to differentiate it from an infantry class, so I think renaming it is necessary.