I was going to start this last night and forgot, I'll expand more once I am not at work and thus have my book in front of me so I can put the page numbers/source.

The idea here is to get a timeline going of recent and important events as they pertain to the Deathwatch game. This should include all dates found in official FFG books, as well as things we may find useful from other 40k sources.

745.M41 - Breaking of the great Hive Fleet Behemoth (suspected source of Hive Fleed Dagon)
755.M41 - Warp Gate discovered by the "Spear of Tarsus"
777.M41 - Achilus Crusade Begins
786.M41 - Vengeance Class Grand Cruiser "Proclamation of Wrath" lost, including the Lord Militant Achilus
812.M41 - Astropathic communications begin to blink out in the Orpheus Salient, Tyranids discovered in the Reach
814.M41 - Tyranids assigned name Hive Fleet Dagon by Lord Militant Tetrachus, Deathwatch warship Thunder's world encounteres two Tyranid drone ships in the orbit of Freya's moons
817.M41 - ++CURRENT DATE++ Dark spores begin to fall on the planet of Castobel

(again, I'll add the source/page numbers in the future)

I'll update this as people find and post more. Please include the source and the date. This is not to replace some of the very extensive 40k timelines out there, rather give a more focused one so people can more easily get a feel for the setting.

++ And I just realized this forum software won't let you edit your posts after a period of time...making projects like this a bit hard. /grumble

Apologies for mining this older post, but it seemed relevant to my question: do we know why the setting for Deathwatch is more than 200 years prior to the (approximate) current date of the 40K setting? I ask out of curiosity more than anything; we've already decided that for our game we're using the current era (early M42), but I wonder if the designers have mentioned this or explained why they chose this time period.

Direach said:

I'm not certain why, but all the 40kRPGs occur at a similar point in the timeline (Dark Heresy is 815.M41, Rogue Trader is 816.M41)

It occurred to me that GW might have said the RPG's had to be set well before their "current" timeline to avoid any conflicts with their current and future plans... but that seems unusually fussy even for GW.