And now, the
grand finale:
Turn 4The sudden appearance of Eldar alongside the Sons of Horus brought a renewed sense of righteous fury in the imperial hearts! All 4 remaining Leman Russ let loose with all their weapon systems on the land speeders, leaving 3 wrecked ones and forcing the last to seek cover.
The regimental commander, however wasn't able to take the initative to its fullest potential,though he pooled his efforts with the Grenadiers and wiped out 40% of the Scimitar Jetbike formation that was pressuring his right flank.
The rebel forces, in a succession of perfectly coordinated events, executed an assault from the Breachers, Fellblade and Terminators on the Ultramarine formation, which were in a blocking position to defend the Titan. The loyalist Astartes lost 2 land raiders and a full squad, but stood their ground and took out half the Breachers.
The surviving O sentinel, desperately trying to prevent a renewed assault on the marines, showed commendable initiative, by rapidly moving over the stream, to block the opposition, but its previous damage was too severe and it was taken by the rushing waters, another imperial hero dead in the line of duty in these foul times..

The Sons of Horus' squads then charged the Ultramarines. With heavy casualties on both sides, the traitors finally carried the day and consolidated their position, beating back a rough rider counter-attack with the support of their terminators, which was instrumental in wiping out the horse-mounted rough riders.

The end was near, and a new assault from the xenos filth left nothing but burning wrecks of the Leman Russ, with light Eldar casualties.
At the end of turn 4:

With the situation lost, Captain Klein, 334th Rough Rider Bikers, gunned the throttle on his bikes, and got to Anvil of the Emperor, detonating the explosive charges attached to the titan's plasma reactors.

The fireball was seen from space...
The events that shortly after took place on Terra and the Imperial Palace ensured that Stricke was to see no more imperial presence for millenia to come...