Province Capture
The actual front line — standing there is the order.
THE CAPTURE MARKER
Every province has a capture marker (~500 m radius, matching the 1 km zone shown on the map). A hostile stack entering it starts a capture attempt automatically — no separate order exists; standing there is the order. An unclaimed province can be captured by anyone; an owned one only by someone at war with the current owner. Capture takes 1 in-game hour of continuous, uncontested presence by a single attacking side.
A STATE MACHINE, NOT A COUNTDOWN

Both sides in the zone at once → contested: progress pauses, preserved. A different attacker becomes sole occupant → the original attempt is cancelled outright; no partial credit transfers. The capturing side ends up with zero units in the zone → hard reset to zero. The hour elapses uncontested → ownership flips immediately.
