Your first chance to build a human base although it's not a very complex one. Still, I like base missions better than squad type action. Begin by training some extra peasants. I trained two additional peasants and put them on gold duty and made four extra to be chopping wood. Now that the economy's taken care of I built one final peasant to construct the buildings I needed. You may want to upgrade the scout towers around your base to guard towers as they are fairly useless as they are. Uther will be patrolling your base so not a lot stands a chance against it (he's level 10) but his kills do take a while and he can end up trying to hold of multiple enemies alone which can allow them to deal some damage to structures. So, until you get the towers up, have Arthas help.

When you're comfortable with your base's defenses (towers upgraded and repaired, barracks constructed - don't finish up the six footmen part of the quest) take Arthas to the east of your base and you'll discover a group of riflemen who intend to slay a dragon. This dragon's blood is said to bestow fiery enchantments upon weapons and you really, really want to do this quest!

Optional Quest: Searinox The area where Searinox, the black dragon, is located is revealed to be near the southeast corner of the map. As you are now able to train riflemen I suggest you build about four extra before you attempt to take on Searinox, though you'll undoubtedly have to build more farms in order to do so. It's not so bad to go a little overboard as any units which survive can help you with the rest of the main quest. When you've got enough units to assault Searinox begin the training of the six footmen. You should have Searinox defeated before they're finished constructing. Remembering to have Arthas ready to heal any damaged units is very useful here as Searinox is strong. You'll encounter a whelp or two along the way which shouldn't pose any threat as your riflemen will gun it down almost immediately. Searonix himself is very powerful and Arthas will have to be almost constantly healing your riflemen. I managed to lose no units to his wrath so i had a sizeable army. When you deliver the heart to the dwarves who gave you the quest they will give you the orb of fire. This is a very useful item which grants any hero who holds it +12 fire damage to each of his attacks. The attacks will also damage nearby enemy units in combat. Very cool.

With Searinox defeated and possibly your sixth infantryman on the way (make sure you have enough farms) reform your units at your base and prepare to do some more fighting. Arthas had gained another level and I again chose devotion aura. Now my units are even more well defended and his healing skills can be put to better use. When the sixth footman is completed you will see a cutscene and be given new objectives. Kill the Orcish Blademaster! I did some exploring here first though. I built a few extra riflemen to make a decent second attack group (you are only allowed so many units in one attack group). I took Arthas to the northwest of the base and found a group of creatures I destroyed and found in the leader's corpse a potion of mana.

North of there is a group of murlocs which when defeated will yield you a 'claws of attack +3'. Now Arthas does even more damage. Further exploration revealed an Orcish base on the northern side of the map. I attacked it and slightly regretted it. I lost all but one of the footmen in this battle and used up Arthas' mana potions. No sweat, really. I constructed reinforcements for the lost footmen while Arthas and the remaining soldiers destroyed the Orc base. On the eastern side of the map I found a group of creatures which had a healing potion. It's not all that useful, really.

Finally, with my forces replenished I set off to tackle the Blademaster. In total for this part I had seven footmen and about ten riflemen. Quite a large army. And it really was a slaughter. There were but scant forces protecting the area the blademaster is in (northeast) and the blademaster himself was a wimp. The riflemen ate him up all by themselves practically. Although I did have only a 50/50 chance of killing him first. He did use that mirror image skill. At any rate he died and I didn't lose a single extra soldier.