Kislev's military doctrine is based around dealing with two scenarios: one, that some sort of raider band or nasty gribbly has crossed the border and needs to be exterminated quickly before it wipes out a few villages, or two, that a powerful Chaos Lord or Higher Daemon or Everchosen has arisen and every fucker in the arctic circle is pouring into Kislev. In scenario one, the Gospodar Winged Lancers and Ungol Horse Archers are an incredibly potent counter to just about anything, because there's very few forces on the planet that are both fast enough to catch up to a Horse Archer and tough enough to withstand a Winged Lancer charge. In scenario two, it comes down to a siege that will stretch on for months at one of four heavily fortified locations that are linked by the only well-built and maintained roads which gives plenty of time for all of the infantry forces in Kislev to be delivered to the battlefield. In the current era Kislev's only professional infantry are the Kreml Guard and the Streltsi of Erengrad, but it's literally a crime for any adult male citizen of Kislev to not own, maintain, and practice with at least one weapon, so Kislev's unmounted militia is not to be written off. In scenario one, the Ice Witches aren't needed. In scenario two, they can easily get to where they're needed, either on a sensible pace on horseback or in a carriage or cart or sleigh or even just by walking.
This is not a typical scenario Kislev faces, but at the end of the day it really isn't a big deal on a national scale. Kislev could afford to leave the issue to the Boyar. If it came down to it, Kislev could afford to just picket the forest and wait for the interlopers to either emerge and have a fight on Kislev's terms, or to get bored and leave. Worst case scenario, they have to refound the Shirokij villages afterwards and firewood and venison is slightly dearer in Kislev City for a year or two. The reason that isn't happening, and the reason that there's such a scramble to get forces in place, is because the current Tzar treats battles as his favourite hobby. He isn't riding at all speed down here because this is some big emergency, he's coming here because otherwise he might miss the fun.
This is not a typical scenario Kislev faces, but at the end of the day it really isn't a big deal on a national scale. Kislev could afford to leave the issue to the Boyar. If it came down to it, Kislev could afford to just picket the forest and wait for the interlopers to either emerge and have a fight on Kislev's terms, or to get bored and leave. Worst case scenario, they have to refound the Shirokij villages afterwards and firewood and venison is slightly dearer in Kislev City for a year or two. The reason that isn't happening, and the reason that there's such a scramble to get forces in place, is because the current Tzar treats battles as his favourite hobby. He isn't riding at all speed down here because this is some big emergency, he's coming here because otherwise he might miss the fun.