March of the Dead

Walkthrough
Wondering the beach to the south of Raven Rock, near the Old Attius Farm, the Dragonborn will stumble into a fight between Redoran Guards and Ash Spawn. This automatically launches the quest.

Kill the ash spawn attacking Captain Veleth
Help Captain Veleth fight off the three Ash Spawn.

Speak to Captain Veleth
The Captain will explain that the attacks of the Ash Spawn have been becoming more and more organized and dangerous, originating from somewhere to the south-east, and that he was trying to find clues to what is going on.

Search the Attius Farm for clues
Captain Veleth asks the Dragonborn to help search for information. As it turns out there is nothing to be found on the long-abandoned farm, but in one of the ash piles, left behind by a killed ash spawn, there is a note, a Declaration of War.

Give the note to Captain Veleth
Reading the Declaration of War the captain finally has a clue to what is happening. Apparently a General Falx Carius is leading an attack on Raven Rock from Fort Frostmoth using the Ash Spawn as soldiers. There is only one thing strange about all of this, the general has been dead for around hundred years.

Kill General Falx Carius
It becomes clear that the Dragonborn must travel to Fort Frostmoth and take out the general there. Easier said than done since the crumbling fort is infested by Ash Spawn, and the direct path to the general is barricaded.

Return to Captain Veleth
Return to Captain Veleth in Raven Rock and tell him that the general is no more. Collect the reward.

Search General Carius's remains
Apparently, should the Dragonborn find Fort Frostmoth before this quest begins and kill General Falx Carius the quest plays out slightly differently. Search the remains of the general to find out what all this is about.

Read the note
Read the note.

Bring the note to a guard in Raven Rock
Talk to the guards in Raven Rock, informing them about General Falx Carius and that the attacks will no longer occur.

Give the note to Captain Veleth
To finally be directed to Captain Veleth.

Marsch der Toten