Changes

When the [[Horus Heresy|Heresy]] began, the Grenadiers were among the [[Imperial]] forces stationed on [[Hydra Cordatus]]' defending the [[Cadmean Citadel]], when the [[Iron Warriors]] [[First Siege of Hydra Cordatus|invadedthat world]] the world. The [[33rd Grand Battalion]], led by [[Space Marine Captain|Siege Captain]] [[Ascari Valkar|Valkar]], and the [[Tyranthikos]], led by the veteran [[Galan Dion|Dion]] were the first of the Iron Warriors' forces to attack the Citadel. The Grenadiers defended it, along with the [[Imperial Fists]]' 42nd [[Space Marine 42nd Company(Imperial Fists Legion)|42nd Company]] and the [[Mechanicum]], with the [[Regiment]] regiment's soldiers striking from hidden underground bunkers. As the Iron Warriors neared them, the Grenadiers were able to kill dozens of the traitors, before the Iron Warriors found the bunkers and destroyed them.{{Fn|1}}