What if the Germans used gas for the first time at Verdun? Initial tests still occur on the Eastern Front, with secondary tests occurring against Serbia. Also to make things a bit more interesting, the attack occurs on the 29th of February, meaning the the build up happens under the cover of storm and the troops are not delayed ten days and forced to spend it in bunkers. This means the troops are fresh and ready for a fight instead of tired, sick, and hungry. Does this give the Germans the edge to breakthrough to the city proper?