Warcraft III: Reign of Chaos/March of the Scourge

Mission Objectives

 * Main Quest: Defend Hearthglen
 * Survive for 30 minutes
 * Optional Quest: Grain Caravan
 * Destroy the grain caravan before it gets to last village

Summary
Under no circumstances launch an attack on the Undead base. It's trouble that's not worth anything. There's a gold mine to the north of your base you could expand into. That's not advised either.

Train 4 peasants for lumber and focus on upgrading your existing units. Develop your preexisting units into a mobile force that moves to meet the undead attackers.

At each exit, build 6 Guard Towers and leave a Peasant for auto-repair. Don't bother with advanced buildings unless you're good with defense. At that point, build the Arcane Sanctum first to upgrade and train more Priests.

If you want to deal with the optional quest, Arthas can handle the Meat Wagons solo with Divine Shield activated.

When the final attack comes, all you have to do is hold out long to keep one building standing when the counter hits zero.

Strategy
Focus your resources on a small party of defenders that move from gate to gate, upgrades, and guard towers. The waves of attacks follow a repeatable pattern, so for extra help refer to the list of attack times and locations below.

Initial Undead Attack
The level starts with an attack underway. Quickly select all of your current troops (give them a quick key) and start focusing on individual undead attackers. You will probably manage to keep all of your or at least most of your starting troops.

Upgrades and Guard Towers
As soon as you abate the initial attack, start focusing on improving your defenses. Don't spend to much money on farms and extra men; instead, invest your current gold and wood in 4 peasants up front and upgrades. Send 3 of the peasants to the gates (one each), and put them in auto-repair mode. Send the fourth peasant to help gather lumber. In the mean time, start upgrading everything you possibly can. Without building extra structures, this means the Blacksmith upgrades (weaponry and armor), Woodmill upgrades (masonry and harvesting), and some Barracks upgrades. As you are able, add more Guard Towers at the gates (aim to have 6 at each gate within the first 5 to 8 minutes), max out your upgrades, and build three or more farms as your resources allow. Remember, you can adequately defend the town with a single party that travels between the heavily Towered gates. There is at least a minute between attacks, usually closer to two minutes, which should give you time to cast some healing spells and make sure the peasant is repairing the towers before doing it again.

The Core Party
Keep you core party handy. In between attacks gather them in the center of the town so that they are equidistant from the three gates. You can also reference the table below and anticipate the attacks at certain gates.

You have one Priest, who is extremely useful in auto-healing your men. Make sure you heal him as your first priority. As you get down to 10 minutes, you might want to see if you can manage building an Arcane Sanctum, and improve the Priests' healing ability, as well as provide a Priest at every gate.

Optional Quest
When the optional quest comes, you should be able to send Arthas out alone to take care of it. Wait a little bit, though, otherwise you have a long way to travel. Wait for at least the first town to fall, in the upper left corner of the map. Consult the table below and try to pick a longer interval between attacks, to minimize Arthas' absence. When ready, send Arthas out to meet the caravan. He should not run into any other trouble along the way. Have him target a Meat Wagon (you only have to destroy the Meat Wagons to fulfill the quest), and activate his Divine Shield just as the undead start attacking. If you have the level 3 Divine Shield (which the walkthrough has advised you to do), you should be able to take out three Wagons before running away and lowering the Shield. You'll be pushing it, so don't activate until the last second. Keep Arthas out of harm's way until he can cast Divine Shield again, and send him back in for the last two Wagons. Then get back to town. The last Wagon will drop a Town Portal scroll, but by now you probably have some good permanent items you don't want to part with. But you will get back much quicker, because in the mean time the town has had to defend itself without Arthas, through two or more waves. Your reward is a medallion of courage.

Final Wave
The final wave comes on at less than a minute remaining. In anticipation, try to get as many extra hands on deck as your resources allow. The farms you set up earlier will allow several more people, but money and wood may say otherwise. The goal, however, is to simply make sure at least one building is still standing at the end of the countdown. Arthas doesn't even need to survive; just put up a good fight to delay the undead for as long as your able. Uther will return and put everything in order.

Attack Times
All times are in remaining minutes and seconds before Uther's return, which can be found in the upper right corner of the screen.

Treasures

 * Jaina's treasures will be available at the start of the game in the middle of the town.
 * At the bottom of the map from where Arthas comes from, the southern entrance of the town, there are 3 villagers to be recruited as footmen.
 * To the bottom-right of the town is a destructible building which reveals a crate which reveals a sheep which reveals a potion of restoration.
 * There is a group of villagers at the bottom of the map very near the western entrance who will convert to zombies(~3s) when approached, kill them before they convert for a easy scroll of protection.
 * If you have the time, travel westwards to right below the purple undead base where there is a small group of Murlocs guarding a cage, defeat them and release the villager within the cage and the grateful man will give you a boot of speed.