The Space Wolves were one of the twenty Space Marine Legions, being led by their Primarch Leman Russ. After the Horus Heresy and the resultant reforms, the legion was divided into two chapters: the new Space Wolves chapter retained the name of their parent Legion, while the second chapter took on the name of the Wolf Brothers. The latter however suffered from mutation and was disbanded. It is currently unknown if there are any other descendant chapters of the Space Wolves at all. The twelve Great Companies are a defiance of the standardized Codex laid out by Roboute Guilliman. Each Great Company is based in the Fang, the Space Wolves Chapter Fortress and is led by a Wolf Lord,who answers only to the Great Wolf. Each Great Company is fully self-contained, made up of a body of fully armed troops as well as the spacecraft necessary to transport the Great Company. They each also have their own forges and customs. The size of each Great Company is unknown but the Space Wolves Legion was said to be one of the smaller Legions. As each Great Company serves as an independent army, they maintain a much greater number of troops as opposed to codex companies. Speculation has ranged from between 150 and 1000 marines per Great Company. Each Great Company is made of a number of packs that function much like a Space Marine squad. However, their tactical usage varies greatly. Each squad is unique in that it doesn't ever receive reinforcements, making the higher level squads smaller in number compared to the lowest Blood Claw pack. Many Blood Claw packs start with as many as fifteen marines. However, losses take their toll, and by the time a Blood Claw squad reaches the level of Grey Hunter, normally only 9 or 10 are left. As they age, further losses limit the squad sizes of Long Fangs down to just 5 or less.