Transactional email campaigns

hi all, 
currently in the process of migrating all of our transactional emails to marketo & we're wondering on:

if we need to build a campaign for each of the emails, or if the API triggered campaign that we've built will trigger all the emails in the assets folder, under the one program?

any help is greatly appreciated. thanks, Mike

p.s. 

they would all have the same campaign steps, so it would be good if we can just use the one, that applies to all email