The Eastern Invasion is a beginner-level campaign which is about a knight named Gweddry, assigned to guard the southern outpost of the River Guard.
"It was the thirteenth year of Konrad II's reign, and there were strange occurrences in the Estmark Hills on the eastern border of Wesnoth.
Cattle and beasts of burden were found dead in the fields, and men went missing from their houses, with no clues but a thin stream of black blood. At first the settlers suspected raiders from the great desert, but when they sent scouts east they found nothing but a small mountain range and miles of swamp.
The disappearances did not stop, and every day the terror grew greater. Eventually, the people living in the eastern villages sent a messenger to the King, asking for help. The messenger rode hard for many days and nights, and finally reached the city of Weldyn.
When the King received news of the problem, his advisor Dacyn had much to say. Apparently, these attacks were connected to similar ones that occurred earlier on the far southern border, attacks by undead. Dacyn outlined a plan to combine these intrusions.
In the days of the king Garard I, two strong points had been built along the near bank of Weldyn, south of Soradoc, to stop bandits and orcish raiders out of the Estmarks from entering Wesnoth. But in later years the River Guard posts had been abandoned, as colonists spread into the Estmarks and the orcs were driven in retreat north of the Great River.
With unknown enemies pressing Wesnoth from the East, Konrad II decided to re-build and re-man the River Guard outposts, and use them to keep the Crown's eye and hand firmly on the settled country to either side of the lower Weldyn. He sent two of the most promising young officers to them.
To the northern outpost he sent Owaec, a clan noble. To the southern outpost, he sent Gweddry, who could be accompanied by Dacyn the mage. It is with them this story is concerned.
All went well once the King's forces arrived. There were no attacks for several weeks, and Gweddry's men started to grow incautious. Then, at dawn one day, Gweddry and his men were roused by the startled cries of the night watchmen..."
A large group of undead appear at the border, and Gweddry must hold them off for some time before reinforcements come.
At the beginning:
Gweddry: What? What is going on?
Dacyn: Look. To the east. Undead approach! But wait...I sense something...They must not see me...
Mal-Ravanal: Hm. I do not sense anything out of the ordinary here. My scouts must have deceived me. Very well, destroy them.
Mal-Sakkat: Very well, Dark Archon. They will die. And then?
Mal-Ravanal: On with the search. I trust you can defeat these men yourself? I have no time to waste here.
Gweddry: What?! Men, to arms! And where did Dacyn go?! Gweddry: There are too many undead, I cannot defeat them...but my orders are to hold this outpost at all costs. It may be we will die this day. Gweddry: But...somehow, I do not think Dacyn has abandoned us. He must have had some reason for leaving.