to fight partisans i use cavalary only as they have highest chance to catch them ( and some have anti-partisan skill) , using 2-3 regiments per anti partisan stack, and depending on regions, sometimes i use up to 10! these atipartisan stacks, and they are not only stationed in cities to protect them, but in regions in which they simply love to spawn, stationed in lvl 2-4 depots ( to keep thep suplied not only with food, but mainly ammo) , and as bonus protect them from harsh weather
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and yes, freqvency of some spawns, especialy of greens in some areas is realy annoing. main counter to this by me is to play only loaylity incresing decisions and never recruits/money requisition.