In Modern Conquest it is possible to join in a union with other players.
Everyone, who is currently not in a union, can establish or join one. Leaving a union is possible at any time.
Every union will receive their own forum, where members can create private topics only visible to other members.

There are 3 different types of unions:
Free unionnono
Leader unionyesno
Despotic unionyesyes
Unions that require a leader will be disbanded if the leader decides to leave.
A union that does not require a leader will remain when the leader leaves.
Unions without members cannot exist. As soon as the last member leaves, the union will be disbanded.
The leader of a union cannot hand over leadership to others.

The founder of a union will always keep his administrative rights on the union forum even after leaving the union.
At the end of every round or whenever a union is being disbanded, all private topics from the forum will be deleted while the public ones are moved to the general union forum.

A union leader can expel members at any time.
In order to decide who can join and who can't, the union founder can set a password for joining.
If there is no password set, joining the union will be free for all.
This, however, does not apply to despotic unions. The only way to join is to send a request to the leader on the union screen.

When establishing a union the founder can choose a common treaty, but does not have to.
Every player accepts a common treaty as soon as he joins the union.
Previously signed private treaties with members of the union may be replaced. However, no private treaties will be terminated.
When involved into a conflict, common and private treaties are of equal value.
Contradictory ties in a conflict will force the player to remain neutral, as it is the case with private treaties.
The following treaties can be chosen from:
DescriptionAttack clauseDefense clauseAttackprohibition
Alliance union treatyyesyesyes
Anti-aggression union treatynoyesyes
Non-aggression union treatynonoyes
Fragile Alliance union treatyyesyesno
Common treaties cannot be cancelled by a player while being part of the union.
All of the common treaties of a player, who leaves a union, will be downgraded to private ones.

Common treaties can also be signed between unions by their founders on the union screen.
The cancellation of a treaty also has to be done by the founder of a union.
In such a case the existing common treaties will be downgraded to private ones, thus remaining in place.