Is there a general strategy I can employ in campaign mode?

I am finding it difficult (not as difficult in skirmish mode)-- it seems the computer has larger armies, more
characters, and they seem to be able to see the whole map when I cannot.

Is is a war of attrition (just keep building up?), or lure them into traps, or go for a quick victory?

I would like to beat all the campaigns in all the Hmm games, but I am struggling on campaign modes.

Great game in skirmishes and great game in general!

Thanks for your feedback.

Do you mean HoMM3?

The main tip for campaign mode is this: Heroes transfer. So try and get all the permanent boosts and spells before finishing the level.

When, for example, the enemy has only one town left and is all but defeated, have a hero with a large army camp at the gates so he doesn't get out, then spend some time with transferable heroes to visit all the permanent boosts they missed.

If you mean HoMM 1 or 2, this doesn't apply.

Don't be afraid to fight with neutral armies. If you wait too long, you won't have the appropriate resources to develop your army and the computer will finally overwhelm you. When you conquer an enemy town don't return to your castle for reinforcements. Instead use the relay tactic. Hire a new hero in your starting town, recruit new creatures and send him to your main hero that's holding up near the conquered city. If you really can't keep up, then you can use this walkthrough: https://www.celestialheavens.com/viewpage.php?id=119.

Restoration of Erathia campaigns are easy. Wait until you see the Armageddon's Blade ones... :) If we're talking about HoMM3 that is.

Thanks so much for the help.

I have played all the HMM games (2 and 3 are my favorites), but mostly in skirmish mode.

I think I am going to try the relay strategy to grp up armies. I was getting overwhelmed in hmm1 towards the middle

of the game, the computer just seemed so much more efficient than I was.

Is it an unreasonable goal to be able to beat all the campaign modes in all the games I wonder?

Later maps in the campaigns are going to be more difficult; the AI often has more and more starting castles/forces than you do.

Sometimes you'll need to use attrition and wipe out small portions of the AI armies while preserving your forces, sometimes you'll need to lure the AI into mismatched battles where you are in a position of strength (Town Portal to an empty town when the AI approaches to take it, or defending a castle with lots of ranged units against the AI's walker army), sometimes you need to hang back and let the AI factions weaken each other. In pretty much every case, you'll need to be very aggressive about moving out and capturing things (even if you don't expect to hold them) while taking minimal losses. As your supply lines get longer, remember that you can hire extra heroes to effectively create a chain. Position each link in the chain such that the previous hero spends his last move point on initiating contact with the next hero in the chain, pass the creatures to the next hero, and then the next hero starts HIS trip to the front lines.

In HoMM1, Barbarians make better supply chain heroes because they have no movement penalty across any terrain.

Also, remember that you can mix creatures from different castles. Iirc, in HoMM1, you should be able to mix from two different castles without a morale penalty. Knight's have a morale bonus, so using a Knight will allow you to mix in an extra castle's creatures. Use the strongest creature stacks from a few different castles, and don't be afraid to switch to the creatures of a different castle type if you have a lot of creatures available from that castle type (ex. if you have lots of Barbarian castles, but only one Warlock castle, then consider switching to Barbarian creatures instead of Warlock creatures). No. All of the campaigns can be beaten, though it may take a lot of time to get through them all.

For completeness, in case readers want to know about later games (and these notes may apply to HoMM1, but I have never played it, so they might not):

In Heroes 2 and in Heroes 3, the morale formula is: +1 - number_of_factions_beyond_1. So if you have only one faction, +1 - 0 => morale bonus of +1 for "All troops of one alignment". If you have two factions, +1 - 1 => morale modifier of 0. If you have three factions, +1 - 2 => morale penalty of -1 for "Troops of three alignments". It goes on from there. Note also that undead are unaffected by morale, but that the mere presence of undead has its own -1 penalty, so mixing undead with living troops gets you +1 - 1 (two alignments) - 1 (undead in party) => morale penalty of -1. To get the worst morale, use at least four alignments, and have one of those be undead: +1 - 3 (four alignments) - 1 (undead in party) => morale penalty of -3.

As Bookwyrm says, you can use the morale bonus from Leadership (a standard skill on Knights, and can be learned by many other hero types) to counter the penalty. Each level of Leadership gives you +1, so an Expert Leadership gives +3. This can allow you to mix wildly different armies, or give you a substantial morale boost if you use armies with very few factions. In some cases, you can also obtain artifacts that improve morale.

Morale greater than 3 is capped at 3. Morale less than -3 is capped at -3. If your configuration would exceed those caps, you can take morale reduction penalties without consequence until you no longer exceed the cap. For example, if you had Expert Leadership (+3), there is no reason not to take a troop of a second (non-undead) alignment, because you would go from (3 + 1) => 4 => 3 down to (3 + 0) => 3. If you had Expert Leadership and an artifact of +2 morale, your uncapped morale would be 5, so you could take a -2 penalty and still have the best effective morale.

Of note: I referenced the Knight morale bonus specifically for HoMM1. In that game, individual heroes do not have skills, instead each class of hero has a specific bonus. Knights have +1 morale, Barbarians ignore the movement penalty for all land terrain (so they'll move faster across snow, desert, etc. than a similarly equipped non-Barbarian), Sorceresses get bonus movement while on boats, and Warlocks have +1 scouting range.

The rest of your post is spot-on for HoMM2 and 3.

I love this community!

Thanks so much for taking time out of your day and share those thoughts with me.

That information is priceless, and I shall champion on with renewed Vigor!

I only know HoMM2's original campaigns (Archibald and Roland) which I enjoyed for their variety of challenges. They are long campaigns - if I remember correctly [EDITED HERE] 8 or 9 missions to complete in each chosen from 11 and 10 respectively. (Archibald's 11 comprise 6 that must be played, 1 optional to earn what will be a really worthwhile advantage for some of the later missions, and 2 either/or pairs. Roland's 10 comprise 7 that must be played, 1 optional to earn what will be a really worthwhile advantage for some of the later missions, and 1 either/or pair.)

Automatic saves when you finish a mission mean you can try both missions in an either/or pair, deciding afterwards which to go forward from.

300 days - game turns on the maps - to finish is "black dragon" score. When beating this (which I've done with both campaigns) then (in each campaign) the first mission was one of my slowest. Usually the computer has the advantage of numbers, but often you start with an advantage of your own, for example some extra, much better troops in the second mission. So make the most of this quickly; the longer you take the harder things can get. Cherry pick nearby resources, go for more distant ones first before the computer gets them, or attack its castles while its heroes are out foraging.

In each campaign, "find the crown" is the one mission you can fail through no fault of your own, if the randomly chosen hiding place is too close to the computer's starting castle - and this one the computer does cheat at, recognising at least the general area to go for from far too few obelisks visited. Fortunately this mission is one of an either/or choice, and done right the alternate mission's pay-off is much more valuable. (That's my opinion.) - what HoMM2 calls "wandering armies" but I think of as blocking mobs. Some are scripted, but many are random choice of creature, not necessarily hostile - there's a chance they'd rather jump aboard your bandwagon than fight your hero to the death. So my tip is always - well, nearly always - attack them with heroes who have room for recruits. Then if they're more hindrance than help in that army, they may still be worth swapping out to another hero or into a castle garrison.

(This is quite separate from the specialist skill for buying off mobs that decided they are hostile.)

Another tip - you go first. This means if you capture a town on the first day of a new week, you can take the week's new recruits there before the computer has time to.

The consensus on YouTube playthroughs I've watched - still discussing HoMM2 Archibald and Roland - is to have one lead hero who does all the fighting (with one big army) so as to gain maximum levels, while secondary heroes starved of experience not only run the supply chain, but also serve as expendable scouts revealing the map. Against the computer in campaigns, I disagree - a more flexible approach worked for me.