effect · add_core_of

Hands-On Usage

add_core_of is commonly used in territorial expansion mods. When a country acquires a state through events, decisions, or post-war peace settlements, you typically grant that country a core on the state simultaneously to eliminate integration penalties from non-core territory. For example, in the completion event of a "Greater Poland Plan" style mod decision, you can batch-set historical claim states as cores:

# Execute within STATE scope
123 = {  # Enter target state scope
    add_core_of = GER  # Set this state as a German core
}

You can also use it together with [set_state_owner_to](/wiki/effect/set_state_owner_to) to complete territory transfer and core assignment in a single event.

Synergy

• [set_state_owner_to](/wiki/effect/set_state_owner_to): When transferring state ownership, it's standard practice to call add_core_of simultaneously to prevent the new territory from remaining non-core for extended periods and triggering integration penalties.
• [remove_core_of](/wiki/effect/remove_core_of): In territory exchange scenarios, you typically use remove_core_of to revoke the old sovereign's core while using add_core_of to grant the new country a core, maintaining logical consistency.
• [is_core_of](/wiki/trigger/is_core_of): Used within limit or trigger blocks to verify whether a core already exists, preventing duplicate triggers or serving as a prerequisite for subsequent events.
• [is_claimed_by](/wiki/trigger/is_claimed_by): Frequently paired with add_core_of to check claims. If a state is already claimed, you can upgrade it to a core, allowing you to design multi-stage story chains progressing from claim to core.

Common Pitfalls

1. Incorrect scope hierarchy: add_core_of must be called within a STATE scope. Beginners often write add_core_of = GER directly in COUNTRY scope without first entering the state scope, resulting in script errors or silent failures. The correct approach is to first enter the corresponding STATE scope using a state ID or methods like every_neighbor_state, then execute the command.
2. Providing a country tag instead of a variable as TARGET: The target of add_core_of must be a country (such as GER, THIS, or ROOT), not a state ID or province ID. If you need to dynamically reference the current event trigger country, use keywords like ROOT or FROM. Hardcoding an incorrect tag will fail to add the core and produce no error message whatsoever.