Under Pressure by John Wilson

Issue: 27
System: Harpoon
Publisher: Game Designers Workshop

Under Pressure
by John Wilson

One thing which has puzzled me is the lack of science-fiction naval wargames. All other forms of warfare are covered by science fiction games, while there are naval rules for every period bar SF. Bummer... So, as a fan of Harpoon, I decided to rectify the situation and write a scenario that would be appropriate.

I don't know how many SF gamers actually own copies of Harpoon, so I have included explanations of the statistics. All distances and speeds are given in nautical miles (1nm = 2000yds = 1800m). All other data are given in metric units.


Earth is under threat of invasion by a group of aliens known as the Reticulans. The initial invasion fleet was destroyed by a nuclear strike. Now, the Reticulans have embarked on a program to locate and destroy the Terran weapons before attempting another mass landing. As their orbital sensors have great difficulty in penetrating the oceans, the Terrans have placed their nuclear defences in submarines and undersea forts.

Missile Base 221 is an underwater missile silo belonging to the European Union. It contains the launching facilities for 10 ICBMs which are each capable of delivering six warheads anywhere within 6000nm. In order for the Reticulans to gain a foothold in the European sector, it is essential that Missile Base 221 be eliminated.


Missile Base 221 is located in the North Sea at a depth of 100 fathoms (0.1nm). The surrounding seabed is flat, with no distinguishing features. The area used for this scenario should represent an area of 60nm by 60nm. Available depths are Surface, Periscope, Shallow and Intermediate.

Terran Forces

Orders: Missile Base 221 is an essential linchpin of the European Defence Network. Therefore it must be safeguarded from attack. Any vessels that approach within 30nm of Missile Base 221 are to be challenged. Any who approach within 20nm or use hostile force within 30nm of Missile Base 221 are to be terminated.

Forces: Two Tebbit Class Hunter-Killer submarines, HMS Norman and HMS Chingford, have been assigned to the defence of Missile Base 221. Additional support may be provided by a surface group and an air group. However, these will take an hour to arrive and should not be considered as available for immediate use.

Setup: Missile Base 221 should be placed at the centre of the gaming table. The two escort submarines should be placed in patrolling patterns within 20nm of the base. Depth, course and speed details are up to the player. The patrolling patterns may not be deviated from until the Reticulans are detected.

Reticulan Forces

Orders: As commander of the Reticulan Scout Vessel N'Tir-Prs you have been assigned the duty of locating any sub-surface missile units in the European Sector. Any such forces are to be destroyed. Failure to do so will result in the delay of our inevitable victory.

Forces: You have command of the RSV N'Tir-Prs.

Setup: The Reticulan player may enter from any edge of the gaming area at any depth and course. Initial speed is limited to 20 knots until an opponent is detected.

Victory Conditions

The Reticulans win if they render inoperative or destroy Missile Base 221. The Terrans win if they can prevent the Reticulans from achieving a victory.

Missile Base 221

Missile Base 221 is an underwater missile silo. It consists of three modules - a Habitation Module, a Service Module and the Missile Silo.

The Habitation Module contains the crew quarters, stores and a 'garage area' for the Missile Base. A hit which penetrates the crew quarters will prevent the Missile Base from carrying out any actions until the area is pumped out. The Service Module houses the life support, powerplant and sensor functions for the base. If the life support is hit then the base will become uninhabitable within 1 hour and any flooding or fires cannot be dealt with. Destruction of the powerplant will prevent the Missile Base from carrying out any actions. A hit to the sensors blinds the base. Note that the sonar has an effective active range of 16nm and an effective passive range of 30nm. Both modules have Heavy Armour and count as Large Targets.

The Missile Silo is sunk deep into the seabed next to the other modules. The only features which emerge above the seabed are the launch doors for the missiles. These can be targeted as if they were Small Targets. Any damage inflicted on the launch doors will flood the silos and render the missiles useless.

A defensive perimeter of command detonated mines has been placed around Missile Base 221 at distances of 5nm and 10nm. These mines have an effective radius of 0.25nm. They are highly effective against torpedoes. Detonation of a mine creates a 0.5nm gap in the defensive perimeter.

Hydrophones have been sown within 5nm of Missile Base 221. Any activity within that area will automatically be pinpointed.

Notes and Assumptions

For those unfamiliar with naval warfare, there are certain differences between it and land/space based warfare. These can really make a difference.

It is assumed that all units on a side can communicate with other units on that side. This is presumably done using either ELF or soundphone communications systems. If the players are feeling really masochistic, then realistic submarine communications may be used.

Underwater detection using passive sonar is problematic. Active sonar is better, but is the equivalent of walking around a battlefield with a bloody big neon sign saying "SHOOT ME!". This scenario was originally intended to be run with realistic sonar rules, otherwise it degenerates into a slugging match. If the rules you are using can cope with hidden movement - do so. Another point is that Missile Base is located under the thermocline (the layer between warm, surface waters and colder, deeper water). Sonar has reduced effectiveness through the thermocline.

Remember that this action takes place underwater. The water pressure at these depths is equal to 10 atmospheres! If the hull of a vessel or the armour of an individual is breached at these depths, the results will almost always be fatal.

Because of the distances and speeds of weapons in naval warfare, it is important to keep track of any missiles and torpedoes launched. It is entirely possible that a fast vessel may outrun a missile, particularly if it is at the extreme edge of its range.

Suggested Figures

Harpoon players may be content to sketch out the action on paper (I usually am). For those who like to use miniatures, try the following. For the Missile Base I would suggest using 1/300 SF buildings. Figures to represent the submarines will have to be snaffled from wherever you can find them. The Reticulans are easy - any organic looking spacecraft and fighter miniatures can be used. The stranger, the better. To represent torpedoes and missiles, I suggest using counters.


This scenario was originally written as a science-fiction based naval warfare scenario for GDW's Harpoon. Depending on the rules used, the scenario can be changed. The original intent of the aliens was to destroy the base to prevent its missiles being used against them. Instead, they might wish to take over the base and launch its missiles against the humans. This could not be done in Harpoon as it has no provision for anything but naval vessels and aircraft.

A further alternative is to substitute a ballistic missile submarine for Missile Base 221 and its defences. Surface vessels may also be used by the Terran forces.

The ultimate version of this scenario would be to allow the Terran player a full support group to assist in the defence of the missile base. While this would be a more accurate situation, it would be a challenge for the Reticulan player.

Harpoon Data Annexes

These data annexes are laid out as in the Harpoon rules. Data not directly relevant to this scenario has been left out for simplicity. In Data Annex A, Speed is in knots. The Damage Mod is an indication of how tough a vessel is. In Annexes E and F, Effective Range is in nm and Speed is in nm per 30 second turn. %hit indicates how likely the weapon is to hit (1.0 being 100%). In Annexes M and MA, all ranges are in nm and % detect is the chance of detection in the given mode of use. CZ indicates how many convergence zones the sensor covers and is only of importance to Harpoon players. Honest.

Annex A - Ships

Tebbit Class SSN
Displacement: 6000
Damage Points: 98
Damage Mod: 1.00Speed: 28/40
Propulsion: NuclearCrew: 100
PB&SB(6)1 Torpedo Tubes
Type T1, Type T2, Type T3
Carries an arsenal of up to 30 Blowfish torpedoes and/or Harpoon missiles. Equipped with anechoic coating and Quieted engines.
Damage and Speed Breakdown:
Displacement: 5000
Damage Points: 86
Damage Mod: 1.00 Speed: 40/60
Propulsion: Anti-Grav Crew: 20
F&A(1)1 Rattler
Type MA1
The N'Tir-Prs, a hastily converted space vessel, uses an Anti-Grav propulsion system to maneuver in the water. This is the equivalent of a Quieted engine. The A-Grav field also provides the equivalent of Special Armour surrounding the vessel. However, if the N'Tir-Prs is subjected to an active sonar sweep, it will be automatically detected. The N'Tir-Prs carries four smaller vessels - known as Remoras by the Terrans. These are hit on a Weapon Mount Critical.
Damage and Speed Breakdown:
Remora Fighter SSAG
Displacement: 200
Damage Points: 10
Damage Mod: 1.00 Speed: 50/100
Propulsion: Anti-Grav Crew: 5
PS&SB(4)1 Missile Rack
Type MA2
Each Remora carries four Lamprey type torpedoes (actually guided missiles, but let's stretch a point). Remoras are modified space fighters. They use a version of teh A-Grav propilsion unit used by N'Tir-Prs. Again this gives them the equivalent of a Quited engine. However, it does not provide amy protection for the vessel, nor does it improve the chances of detection by active sonar.
Damage and Speed Breakdown:

Annex E - Anti Submarine Warfare Systems

NameEffective RangeSpeed%hitDamageRemarks
Rattler10.0/5.0-0.75/1.024/10See below

The Rattler uses a focused beam of sound to do damage to vessels. It may be used either as a focused beam or an area effect weapon. As a focused beam, the Rattler uses the first set of figures given. As an area weapon, it has a cone of effect which is 2.5nm wide at extreme range and affects one depth band. Any objects in the cone are automatically hit and suffer 1 Critical Hit. Armour offers no protection.

Annex F - Torpedos

NameEffective RangeSpeed%hitDamageRemarks
Blowfish15.00.50.8014371Acoustic Homing
Lamprey20.020.255025Badly modified missiles.
Treat them as Homing.

Annex M - Search Sonars

NameCZDirect Path Range%detectRemarks
T1 3 16 25 0.8 0.6
T2 3 20 30 0.8 0.6
T3 2 - 20 - 0.8

Annex MA - Advanced Subsurface Sensors

NameDirect Path Range%detectRemarks
MA1 - 100 - 0.85 See below
MA2 - 20 - 0.85 See below

These sensors work by detection of neutrinos and EM fields. Consequently, any vessel which does not have a nuclear reactor and onboard electronics cannot be detected. Such vessels are few and far between in naval warfare.

Ed Note: Harpoon is a highly popular Moderns Naval Wargame system written by Larry Bond and published by Games Design Workshop. Since GDW's demise, all rights to their games systems have reverted to the authors and I would suspect that given the popularity of the system (both tabletop and computer versions were produced), it won't be long before the game resurfaces in some new format. That said, it is still fairly easy to get hold of the old GDW variant.