Diamat

Diamat is an Ultima armoury world from Fallen Angels, the Heresy prize Horus sent Luther's Dark Angels to seize so siege engines would not reach Isstvan's loyalists. This pin is that Mike Lee forge-stop, not a random Diamat hive.

Zahariel and the Calibanite host took the ordinatus stockpile while the Lion's other war moved elsewhere. Horus wanted the guns. The First Legion learned that a Warmaster's favour is just another ambush with better paperwork. Diamat is not Mars and not a later 40k forge with no Heresy bill.

Diamat still matters as a named Dark Angels logistics wound. Unofficial fan summaries keep the Ultima parent and do not file this row as Caliban, as Isstvan, or as a 41st-millennium Mechanicus shrine.