Which game you playing? Civ3, Civ4, Conquests, Beyond the Sword?

I guess most all Civ games are biased toward defense, particularly Civ4 and BTS.

Best general advise: artillery (catapults, trebuchets, cannons, artillery, bombers, ship bombardment) LOTS OF IT.

In Civ4 you can use arty to reduce city defense, then use one or two to attack frontally to cause collateral damage to multiple units. Then you will be more prone to attack successfully and with more reasonable 'casualties.'

Supposedly the reason they designed these games this way is to promote a "more realistic" simulation of "combined arms."

Where you attacking from a transport directly to a city?  If so that is considered an amphibious assault and your units are -50% power.  Which would explain the modern armor slaughter by the mech inf, which are tough to began with.  Tanks rolling out of transports one by one onto a beach make great targets.  Either  land the tanks onto an adjacent square first and then attack or get the amphibious assault promotion which negates the penalty.  For example Marines have this from the start.

Always pay attention to terrain when attacking and defending.  Hills, forest, and rivers give bonuses to the defender.  Cities give huge bonuses depending on population, culture and defensive improvements.  By the end of the game, huge cities can have over +100% defensive bonus.  So a Mech Inf starts with power 32.  If it is entrenched for +25% and let us say +100% for the city, 32 X 2.25 = 72.  Now modern armor start with a power of 40 and with -50%, they end up as 20.  20 versus 72 is not good odds.  And it seems about right for what happened to you.  Off course the units can have promotions that influence their scores more, but this was an example that terrain has on combat. For example I always get "City Garrison" for my mech infantry, which can give another +20 to 30%.  However the -50% power is the real killer.  Pay attention to the odds that pop up on the bottom left of the screen when you mouse over your target.

If I was trying to take the city you decribe I would land tanks and some artillery next to the city.  Then use the artillery for a few turns to reduce the city defense bonus to as low as possible.  You could also use battleships to pound the city's defenses if you have some handy.  Then attack with the tanks.  This will negate the -50% for an amphibious assault because you are on land (caution: make sure you are not attacking over a river as that counts as an amphibious assualt as well), plus it reduces the city's bonus.  The unit to unit odds will probably still be against you, but it should be much better and you should be able take the city.  40 vs around 50 is much better than 20 vs 70+.  Just landing and attacking the city would probably work too, but reducing the defense with artillery will help you lose less tanks.

The numbers game is new to me, so i'll need to pay more attention to this aspect.  Also, I seldom change my government from Despot when i'm planning world domination-- perhaps this is a whole new forum topic -- but is there a better gov't choice?

Well Scip.... this IS in a Civ3 Discussion forum!!!

My fault.  I had civ 4 in my head.  Although the amphibious assault info still applies.  It has been a long time since I played civ 3.  Maybe another person can help you as far as the combat goes.  Your gov type will not affect individual combats.  I have a long explaination of gov types for civ 3 around here somewhere.  I will try to dig it up.

Edit:  Here it is:

Now I tend to be more of a builder and tech peddler than a warmonger so keep that in mind when I describe the uses of each government.  Some of the local warmongers might have a slightly different point of view. In the original civ 3 there was two main government paths that players would generally take.   despotism/monarchy/communism or despotism/republic/democracy.  The former was used if you planned on fighting a lot of wars because they have good unit support and no war weariness.  The latter was useful for making lots of money and researching tech.  However it is expensive to maintain a large army with a republic or a democracy.  Also during long wars, war weariness becomes a problem.  Some players, especially when playing a religious civ, will switch between communism and democracy.  Depending on if they are at war or not.  Conquest added feudalism and fascism.  These added some more choices for those wishing to have large armies and lots of wars. Anarchy of course is only used when switching governments. Despotism is the starting gov and doesn't really have any good qualities.  High corruption and waste.  You lose 1 food/shield/gold from any square producing more than 2. This is the only form of government that does this so you probably want to switch out of it as soon as possible.  The only positive thing is 4 free units per city no matter what size. Monarchy is for some a stop on the way to communism, but others love this gov and stay in it the entire game.  Corruption and waste is better than despotism but is still pretty bad.  The good news is that you now get all food, shields, gold from worked tiles and instead of sacrificing population to hurry production, you now spend gold.  Unless you have lots of 7+ and 13+ size cities, the unit support isn't better than despotism but the extra gold you now get from your tiles usually makes up for it.  Every unit above your free support cost only one gold so having a large army is ok and there is no war weariness so you can stay at war indefinately.   Use this gov as a stepping stone to higher ones or if you want to fight lots of long wars. Feudalism like I said before is an alternative to monarchy.  It seems to be rarely used and is only useful if you have lots of towns size 6 or less.  Corruption and waste are the same as in monarchy, but instead of spending gold to hurry production you sacrifice population just like despotism.  Since each unit beyond your free support cost 3 gold, the highest of any gov type, you do not want to have more units than what are free.  There is low war weariness but it should not be a factor except for extremely long wars.  Only use this gov if you have lots of towns pop <=6 and prefer to sacrifice population to rush production. Republic is generally used as a stepping stone to democracy.  Although some like to use a despotism/monarchy/democracy path instead.   Unlike other forms of government, military units stationed in cities no longer keep people happy.  You need to have luxuries or gold to spend on culture.  The good news is if you have some decent sized cities you should have the gold you need.  All worked tiles that produce at least one gold, now produce one extra.  Also corruption and waste are less than that in monarchy and feudalism.  You also spend gold to rush production.  The bad news is that free unit support is low and extra units cost 2 gold each.  This means that large armies can get expensive.  However with the extra gold being made, republics can afford it.  However it is money that could be going into tech research.  When in the republic gov I personally tend to keep the army small and use the extra money to stay ahead in techs and keep the units state-of-the-art.  War weariness is the same as feudalism, so long wars are possible.  Although eventually you may have to spend a lot on culture to keep the population happy during a prolonged conflict.  Use this gov type if you prefer a small state-of-the-art military over a larger possibly less high-tech force to conduct wars or wish to spend a lot of gold on research. Democracy is the ultimate money making and tech research gov.  Just like republic each tile produces an extra gold,  you spend gold to rush production and military units do not create happiness.  However corruption and waste is even lower than republic and workers build improvements 50% faster.  Unfortunately there is now no free unit support at all. Although each unit only cost 1 gold so I often break even in unit support when switching from republic to democracy.  Just be aware that every unit you have is costing you 1 gold per turn.  So just like republic, I prefer a small state-of-the-art military.  Democracies have high war weariness and thus can only conduct short wars.  Long wars force democracies to spend lots of gold on culture to keep the people happy.  Use this gov if you want to make lots of money and research tech, and do not plan on going to war much. Communism is good for very large empires or for constant warfare. High free unit support and only 1 gold per extra unit allows communism to support a very large military.  There is also no war weariness so wars can last as long as needed.  However it does not make as much gold for research as republic or democracy.  Corruption and waste is unique for communism.  Unlike all other gov types that figure out corruption and waste for a city based on how far from the capital it is, communism spreads it out evenly among all it's cities.  For example, democracies tend to create a core group of very productive cities around the capital, with outer cites getting weaker and weaker.  Communism makes all cities average, non very strong or very weak.  So it is a matter of taste.  Do you prefer to have a group of very strong cities making lots of gold and building things very quickly while the outer cities barely get by, or have all your cities be mediocre.  Communism sacrifices population to rush production.  Spies under communism are also more effective.  Use this gov if you want a large army and plan on being involved in a lot of wars or if you have many cities and prefer them to all be medicore instead of having a core group of very strong cities and the rest very weak. Fascism is useful if you plan on constant warfare but don't like the communal style of corruption and waste under communism.  High unit support, especially for size 13+ cities and only 1 gold for extra units allow fascism to have large armies. It has the same corruption and waste as republic, but does not have the extra gold per tile.  This allows Fascism to spend a decent amount on research.  Plus since military units in cities produce happiness and there is no war weariness, no money is wasted keeping the people happy during long wars.  You sacrifice population to rush production.  Workers build improvements 100% faster and spies are also more effective like communism.  However when you switch to fascism 1-3 population points are removed from each city to reflect the deportation of all foreignors and undesireables.  Also captured cities produce no culture until the percentage of the population is 100% your people.  Use this gov when you plan on having a large army and fight in a lot of wars, but also want to spend a decent amount of money on tech research and don't mind sacrificing population to rush instead of spending gold.  You also need a lot of very large cities and have to not mind a loss of population in each.  You should also plan on either razing all the cities you conquer or starve them down to a small size to prevent them from flipping back since they will not produce culture for awhile.

Q - is there a better Govt choice
A = Yes. Republic.

* If you have a Civ that cannot just change government in 1 turn, ie you get multiple years of anarchy chose Republic and stick with it.

** Never change spend long periods in anarchy when you are in your Golden Era.  Waste of your best time.

Re 32 MA vs 2 MI.

1. Make sure you only build "Veteran" MAs. Build a barracks first then build your units.

2. Put your MAs into Armies. 

3. IF the city you are attacking is a large city - population over 13+ then the defence value goes up again.

Now this is somewhat fround upon but I do if the results are stupid, as in what you have suffered.

4. IF all else fails, save the game BEFORE you attack, attack and if you find you are losing too many units for no return, STOP and GO BACK to the part you last saved and try again. If that fails, GO BACK and this time DO NOT ATTACK just use your MAs to move around the city destroying the roads and infrastructure.  Surround the city and destroy the food, roads etc.  This will kill off some of the pop.  Save the game and go to the next year and again try and take the city.

Saving the game before attacking saves the BULLSHIT factor popping up.

Cheers

DD. No facism in Civ 3 1.29

That is why:

was in my comments.