This work is a Warhammer fan work.
The Battle of Istvan V, also known as the "Drop Site Massacre", was the most decisive battle in the early days of the Horus Heresy in "Warhammer 40,000". Before this war, Warmaster Horus had used virus bombs to purge his own legion and the other three legions of loyalists on Isstvan III. Later, he led the four legions of the Iron Warriors, Night Lords, Alpha Legion and Word Bearers to openly raise the flag of rebellion on Isstvan V.
The Emperor was furious, and in about 006. M31, seven loyalist legions were sent to quell the rebellion. Among these seven legions, the Iron Hands Salamanders and the Raven Guard were the first to airborne as the vanguard, while the other legions such as the Ultramarines failed to arrive in time due to subspace storms and other factors. This tragic battle ended in a disastrous defeat for the Loyalists. More than 250,000 Loyalist Astartes perished here. The Primarch of the Iron Hands, Ferrus Manus, was personally killed by his former best friend and the Emperor's Son, the Primarch Fulgrim.
The main force of the Ultramarines is delayed by a warp storm
