This might be the hardest map within the OA mod, but definitely the hardest of this chapter. Not only will it demand a lot of work, but it will also demand a lot of your nerves. The script contains many elseif conditions, therefor things will happen, or not, depending how you play the map.

Your main mission is to hold the town of Brusilov (#1 on the map). If you do not succeed, you will lose. The enemy/AI will win if it manages to take it. Losing the other towns won't make you lose, but will have consequences: the enemy will receive reinforcements there that will also go to attack Brusilov. So the more you lose, the worse it might become. It will, however, not be possible to hold them all, but nevertheless, the longer you manage to hold them, the more time you will get to deal with the whole situation and you will need that...

At the start of the map, you will notice there's a few enemy units behind your lines just above the river in the east. You do have some reinforcements in the neighborhood and you can chose to ignore the enemy or immediately prepare for an attack, which is probably the best option. If not, they will go threaten Brusilov from the back. This idea was intent to be a surprise-attack, but can be somewhat annoying. So this is not a spoiler, but something the player should know in advance.

Next, the town Tarasov (#2 on the map) will become attacked. Eventually, it will be impossible to hold this town, but do try to keep it for as long as possible to delay the enemy reinforcements. More attacks will follow, on your left flank, your right flank and on your defenses in front of Brusilov. You should already have started laying mines from the start. Try to close down Brusilov as much as possible, especially the bridge passages and even the town itself.

On your left flank, the enemy will start to attack the town Yastrebenka (#3 on the map). There's three possibilities here: you can choose to retreat your units before the attack or a partly withdrawing of the most valuable units but keeping some to and delay another enemy attack and/or third; you can try to hold it,  only possible by sending support from Lasarevka (#4) and Stariskaya (#5),  probably. It is possible to hold this town, but it will be costly and you will need to fight at your very best. All three possibilities will have different consequences, but holding the town will prevent the enemy reinforcements between Yastrebenka (#3) and Stariskaya (#5) which obviously, makes the overall map a bit easier. Nonetheless, if you lose the town Yastrebenka (#3), you should still be able to win the game.

Losing the towns Lasarevka (#4) and Stariskaya (#5) will also bring more enemy reinforcements that will head for Brusilov. It shouldn't be that hard to hold them. You could also choose to retreat them to Brusilov and have a hard fight there. Who knows, you might manage to survive...

After the enemy attacks are all dealt with, you will need to recapture your lost territory and take out the remaining enemy units from the town in the west.