I see Greek radar towers. They give their owners a 50% combat advantage within a certain radius of the towers. (I think they either increase defense 50% or half your attack strength; I forget exactly what they do except that they are bad for you if the enemy has them nearby.)
AFAIK, nothing in Civ3 'decreases attack strength' as such. But many factors can increase a unit's defence strength (D-value), which is not quite the same thing -- although it has a similar effect:
Terrain:
- Flat tiles: +10%
- Marsh: +20% (C3C)
- Defending across river: +25%
- Forests/ Jungles: +25%
- Hills: +50%
- Volcanoes: +80% (C3C)
- Mountains: +100%
Units outside settlements:
- Unit-fortification: +25%
- Terrain improvements:
- Fortresses: +50%
- Barricades +100%
- Radar towers: +50%(?) to all friendly units within 2 tiles (i.e. in the 5x5 grid) of the tower (not additive between towers)
Units inside settlements:
- Towns (Pop1-6):
- no Walls: +0%
- with Walls: +50%
- Cities (Pop7-12): +50% (replaces Wall-bonus)
- Metropolises (Pop13+): +100%
These bonuses are cumulative -- so for example, when defending a walled Town or a City (+50%) on a Hill (+50%), from an attacker who has to cross a River (+25%):
- a Spear (base D=2), will have an effective D-value of 2 + 125% = 4[.5]
- a Pike (bD=3) would have eD=6[.75]
- a Musket (bD=4) would have eD=9
- a Rifle (bD=6) would have eD=13[.5]
- an Inf (bD=10) would have eD=22[.5](!)
Combat results are rolled based on the total of the Attacker's and Defender's A and eD-values, respectively:
- Attacker's win-prob. per combat round = A/(A+eD)
- Defender's win-prob. per combat round = eD/(a+eD)
...so a Sword attacking a Spear in the above example would actually only have a win-prob. of 3/(3+4[.5]) ≈ 40% per combat round. Generally speaking in Civ3, in engagements between same-era units, full-strength city-defenders are almost always favoured over city-attackers.
That's why 'combined arms' tactics of bombardment -> fast-unit (M-value ≥ 2) attacks -> slow-unit (M=1) attacks are recommended (if possible) when attacking AI towns, especially at higher levels, especially in Vanilla/PtW (where Armies are less overpowered). By first knocking down defenders' HPs with bombardment (zero risk to your units -- albeit a relatively high risk of killing city-pop and destroying buildings in Vanilla/PtW), and/or fast units (50% retreat-prob. if redlined first vs. a 'slow' opponent), you are then less likely to take losses during subsequent assaults, because in order to survive, each successive defender has to win (significantly) more combat rounds in a row than your attacker does.
Extreme example:
A redlined 1HP Spear would have to win 5 combat rounds in a row against a full-strength 5HP eSword, to kill the attacker
before the attacker scored one successful 'hit'. Even if in the situation above -- Spear in a City, on a Hill, eSword attacking across a River -- the Spear would have an overall win-prob. of only 0.6^5 = 0.077, i.e. 8% -- or to look at it another way, it would have a 92% loss-prob.!
If you're playing Conquests, use bombardment and Armies to assault cities. Bombardment will redline mil-units before pop/buildings start taking damage, and as well as being able to draw on the combined HPs of all units in the Army, units loaded into Armies get additional attack- and defence-bonuses based on the Army's size and composition (which are increased if you've also built the Military Academy).
Also, I see a lot of rivers. If you attack across a river your attack strength is halved.
Not exactly -- see above