See attached mission file, or:
Place your player unit and any manned artillery piece - mortar or otherwise - (both BLUFOR for now), name the piece MORTAR1. Some distance away, place a marker called TARGET, and on top of the marker place a trigger with the conditions "Seized by BLUFOR" and "Detected by BLUFOR". In either unit's init line place this code
0 = [] spawn { mortar1 commandArtilleryFire [ markerpos "TARGET", getArtilleryAmmo [mortar1] select 0, 1 ]; };
Start the game, the artillery will fire one round and the game will immediately crash.
If you feel like it, restart the game and try moving the target marker outside of the trigger area, and observe that the game does not crash after the artillery fires.