V 1 would be a lot better choice for dispersal, if they had enough Nerve gas to use.
Then with either V Weapon, you have to deal with the problem of actually deploying those gasses.
Given the existing late War QC issues, you would be having a lot of leaks, not so good for the launch crews.
2nd, the US/UK retaliation with Mustard and Lewisite, plus Anthrax
The Heer will run out of horses for transport very quickly, let alone the men themselves.
War would be over a lot sooner, for the Allies.