I was practicing backups with my colleagues, and we shut down the database twice, reopening it both times with 'resetlogs', without backing it up in between. The database lacked the archivelog it needed for recovery the last time, so we read the docs and prepared to return to a previous incarnation.

We returned to 3 incarnations prior and restored/recovered using:

RMAN> restore database "to_date('9/2/04 23:59:59','mm/dd/yy hr24:mi:ss');
RMAN> recover database "to_date('9/2/04 23:59:59','mm/dd/yy hr24:mi:ss');

What did returning to the prior incarnation gain for us? Seems like I could've just issued the restore/recover commands and performed an incomplete recovery.