#1: What do Tunis, Warshaw, Moscow, Berlin and Marseilles have in common?

difficulty: beginner

The solution:

These 5 territories can be held both from north and south forever and can be part of the stalemate lines at the same time meaning neither side can advance any further. All this results one of these 5 territories are usually the 18th SC someone wants to grab.

Generally Moscow, Warshaw and Tunis is held by southern countries, therefore here are 3 examples where it's occupied by a northern power, as the 18th SC and also being part of the stalemate line.

Examples on Tunis, Warshaw and Moscow:


Marseilles can be held from Piedmont and Gulf of Lyons forever. Western Med from North Africa.
Berlin from Silesia and Prussia, if you have Livonia as well.

Examples on Marseilles, Berlin and Portugal (if you have Portugal, please send me):


Portugal can also be held from the south, even though if Spain is occupied by a northern country, (by attacking both Spain and Mid-Atlantic) but in this case Spain might be grabbed by the southern power(s) meaning this is not a stalemate line from both sides, only from south, which is, of course, enough for a southern power to make Portugal his 18th SC.