In fact it seems that this task is not so easy as described here.
I've been trying to convert a fully functional campaign for RTW 1.2 into 1.3 compatible and still no success.

- As I have lots of new units, firstly the new edb file is empty of units.
I've eliminated all the new buildings from descr_strat, leaving only the original ones.

- I've tried to adapt completely the new descr_strat to that of the imperial campaign in RTW 1.3. This point includes the elimination of
Code:
command 0, ...., subterfuge 0,
from all the characters in the file.
Also changed the rebel generals, eliminating the comma here
Code:
character, sub_faction
and substituting it by a tab.

- The descr_regions file has been also modified: including slaves as resource in all the regions, rome as a resource in Rome, eliminating all the references to romans_julii and slaves as default culture tags.

- I've also included a descr_win_conditions file. Some map_faction have been renamed accordingly to the new names: map_romans_julii, map_greek_cities, map_germans...

Under such conditions, the campaign starts. I can make the movements of the first turns, but it immediately CTD when I press the end_turn button.

P.D.: I've observed that the map.rwm generated in RTW 1.3 is larger than that generated in RTW 1.2.