How the campaigning season shapes a European war against Russia

How long could Russia resist if a naval blunder caused Europe's major powers to declare war?

About six to eight months after a spring attack, with winter potentially adding another six months.

Russia's ability to hold out against a broad European coalition would depend heavily on the campaigning season. A spring offensive could defeat it within roughly six to eight months. If mobilization pushed the attack into winter, weather might buy Russia another six months. The estimate turns on the time needed to organize and move coalition armies rather than on naval resistance alone.