JANUS: A Wargame Simulation Code and the Effects of Nuclear Artillery Yields

In the decades before the wonderful website Nukemap helped us with determining the effects of nuclear weapons when used against any target on the globe, The United States used a Lawrence-Livermore Laboratory program called JANUS. JANUS1 was an interactive wargame simulation code, in which the military could input various yield options on battlefield nuclear weapons, and calculate their effects on enemy forces.

The input would include a simulation of two opposing forces (representing NATO and the Warsaw Pact, respectively) using the colors red and blue. The simulations were ran to try and determine the effects of ER (enhanced radiation) nuclear artillery vs. one kiloton fission weapons. What the simulated wargames determined was that ER weapons caused more casualties among enemy forces than strictly fission weapons.

The simulation also recorded that if the Red Team reached losses between 40-60%, they would discontinue an offensive and rethink their tactics, potentially reorganizing and attacking again. The simulations also brought to light some conclusions deduced by the wargame simulations that could have been used by the United States and NATO:

  • The anticipated use of nuclear weapons by either side affects the character of a game significantly. It determines how Blue will plan his defense and how Red will carry out his offense. It causes both sides to keep large spacings between companies (or platoons), slowing the tempo of the battle.
  • If the employment of nuclear weapons is to have a decided effect on the progress and out come of a battle, each side will have to have an adequate number of nuclear weapons. Without an adequate number, the advantage of a nuclear capability is only temporary. On the average, each side can only count on destroying one combat company per nuclear weapon used, whether it is a 1-kt fission weapon or an ER weapon. Since the enemy has 50 combat companies per division, each nuclear weapon can only destroy 2% of a division. Even after using 10 nuclear weapons, Blue fails to blunt the overall Red capability.
  • In almost all the simulations we ran using JANUS, ER weapons were more effective than 1-kt fission weapons in imposing overall losses on Red. Essentially all the game histories illustrate this. This does not necessarily mean that more Red units were killed per ER -weapon used (which, of course, can be the case) but that the ER weapon causes a greater dispersion of Red forces, helping Blue’s conventional capability. Thus, force massing can be more of a liability with ER weapons than with 1-kt fission weapons.
  • The typical visibility in the JANUS simulation limits either side’s ability to acquire units deep into enemy territory. Thus, neither side had many opportunities to use a 10-kt fission weapon against deep enemy positions. Troop safety constraints limited use of the 10-kt fission weapon between companies that could see each other in direct-fire combat.

In the 3rd conclusion, it was determined that ER weapons were more effective against enemy forces than on-kiloton fission weapons. As stated, this did not mean that the enemy forces lost more soldiers, it was that the ER weapons caused a greater dispersion of said forces. The obvious reason is the reputation of ER weapons, which are better known as “neutron bombs”.

The United States Army, up until 1992 , had two ER weapons in it’s arsenal in Europe: The Lance short range nuclear capable missile, and the W79 warhead, which was a variant of the M422CA1 203mm nuclear artillery shell.

I trained on maintenance procedures on the W79 in Germany in 1991. Whenever I find articles and academic papers published about them, I am immediately drawn in to review if the information is accurate. U.S, Army ER weapons are relics of the past, and thankfully not in existence. There was only one reason to have them, and that was to destroy as many lives as possible, while minimizing static damage to property. They may have been rationalized until the end of the Cold War, but there is no need to return to enhanced radiation weapons in the 21st century.

1.Andre, C G. Look at nuclear artillery yield options using JANUS, a wargame simulation code. United States: N. p., 1982. Web. doi:10.2172/5035071.

Author: Jeff Woodward