Tactics for the Swamp (Fortress).

I haven't tried it yet, but I'm curious, what's better to build in the Fortress (Swamp) on week 1: 1-6 level creatures in the Castle without a level 5 creature, or 1-6 level creatures with a level 5 creature, but in the Stronghold? Could you please advise for future reference (if possible, with justification):smile32: Thank you!