Corvus Umbra

The Corvus Umbra are a Space Marine chapter of the Raven Guard, who were founded in the 14th founding. Their gene-seed came from the Raven Guards. They are horrendously under-strength, barely fielding three companies after the many wars and treasons that have befallen their ranks. Currently led by Chapter Master Insus, the Corvus Umbra lead a thankless existence.

The First War of Silence
The very first engagement the chapter was a part of was against the Thousand Sons on the world of Susor. The Thousand Sons had taken the planet in the hopes of opening a warp-rift and bringing an army of daemons through.

Initial drop
The chapter master of the time, Arcani, ordered a standard planetary drop against the planet's cities in the hopes of dividing the Thousand Sons' attention, while he, the majority 1st company and the librarius would try to attack the leadership of the enemy. As such the planetstrike was divided into four strikes, which each contained approximately 200 marines.

The attacks were underway soon and the marines on the ground reported minor resistance. Arcani was confident and soon ordered a diverging attack from he original strike forces, which were to move and secure major transport and industrial facilities.

These branching forces were only met with minor resistance, and managed to secure their targets with nearly no casualties. This was when Arcani was suspicious. He refused to strike with his own force until the enemy leadership had been found and all enemy forces scouted thourougly.