Named laters and skipping campaigns

[Korvessa]

So if you start with a later campaign (and don't import) do you lose out on the named leaders that appear earlier?
For example, if I start with the 1939 campaign, would Galland ever appear later?
or is he gone forever?

[VirgilInTheSKY]

Chance to get special heroes is one-time only. You skip the campaign, you skip the hero.

[Grondel]

when u start a later campaign u get a force at the start with a bunch of heroes, some of which u can only get this way.