
If the AoE is too large for a major or ambulance to pack up and escape from in the time the sound begins, then it may need a bit of tweaking.
It should have a large AoE, but like the V1, needs an ample enough time for a player to feasibly dodge.
That said, having artillery wipe even an entire army after retreat at base (especially a forward retreat position) is a coup-de-grace move that is very much apart of the game's healthy strategy. If it happens to you, start taking measures to prevent mass retreat situations in the future. Retreat points too close to the front line are notorious for bunching up units.