Battle of Gerio
The battle saw the 6th Company defend the Gerio Stector's strategic lynchpin of Archus, around which all localized Warp Routes passed. Intending to use the flowing warp currents to power an immense summoning ritual, a huge warband of Word Bearers invaded Archus. They fomented rebellion in its cities and began carving its plains into immense summoning runes. A mechanized strike force of the Ultramarines 6th Company made planetfall six weeks into the Chaos invasion and launched a magnificently orchestrated series of armored hit-and-run offensives that eventually saw the traitor forces cut apart and driven into full retreat. Though the Ultramarines force lost 70% of their strength in this grueling war, their incredible victory is commemorated on their company banner to this day.