Battle of Macragge - A New Threat: Over the 10 millennia that passed after the mortal wounding of their Primarch Roboute Guilliman, the Ultramarines defended the Realm of Ultramar against all manner of invaders -- some so strange as to defy the comprehension of the common man.The Ultramarines have tested their might against Ork WAAAGH!s and Renegade uprisings, T'au incursions and Necron raids, but the measure of their heroism is shown truest in battles where they have defended all life in the galaxy itself in the face of threats from beyond known space.So did the Sons of Ultramar prove in the 35th Millennium in battle against the Star-Striders of Crioth, and in retaliation for the Heavenfall Massacres. But of all these terrible wars and heroic struggles, there is one conflict that stands above all others -- the onslaught of Hive Fleet Behemoth against the Chapter's homeworld of Macragge.Thanks to Ordo Xenos Inquisitor Kryptman's discoveries at Tyran Primus, the defenders of Macragge had been forewarned of the horror headed towards them. Upon learning of the threat posed to Ultramar by Hive Fleet Behemoth, Marneus Calgar at once drew up his plans. Deeming Macragge to be the star system most immediately threatened, Calgar ordered its already formidable defences to be further improved. A dozen warships already hung in orbit, and each day more arrived from the Warp. Massive Strike Cruisers cast shadows over civilian vessels and Imperial Navy Destroyers, and were themselves dwarfed by the brooding presence of the Ultramarines' Battle Barges. Between this mighty fleet of warships and the planet's no less formidable orbital defence stations, Macragge was anything but defenceless.Scant solar weeks later, the outrider vessels of the Tyranid fleet attacked Macragge. The alien bio-vessels swept aside attacks by Ultramarines Strike Cruisers and swarmed over the planet below. Soon many thousands of Mycetic Spore-birthed beasts scurried and rampaged across Macragge. Deeming that the Tyranid threat was too massive to be opposed piecemeal, Calgar combined his ground forces into three mighty armies. The primary and secondary taskforces, composed largely of 1st Company Veterans and the regiments of the Ultramaran Planetary Defence Forces, bolstered Macragge's polar fortresses against the Tyranid onslaught. Meanwhile, Calgar's taskforce, the largest of the three, performed a series of rearguard actions, attempting to slow the Tyranid advance and eliminate Hive Mind synapse-control organisms. Calgar achieved great success in the early days of the campaign, buying time with blood for his Battle-Brothers to the north and south. However, the Tyranids kept coming.In a final climactic battle on Cold Steel Ridge, the Ultramarines rearguard was brutalised by the Tyranid horde and Calgar himself was gravely wounded. Knowing that to remain planetside was to doom his followers to wasteful death, Calgar withdrew to the orbiting Battle Barge Octavius. Refusing all but the most vital medical attention, the Master of Macragge took command of the fleet, and sought a way to save his world from certain destruction. Hours later, the main Tyranid fleet arrived at Macragge. With no sign of reinforcements, Calgar led his fleet in a series of daring attacks, striking at isolated vessels as they spread out to invade Macragge in force. Caught between the blistering firepower of Macragge's polar fortresses and the vengeful hammer blows of Calgar's fleet, Tyranid vessels were destroyed by the score, but many more yet remained.As battle raged, the Tyranids unleashed thousands of Mycetic Spores above the vital polar fortresses -- and if the fortresses were taken, Macragge's guns would be silenced, and the world left defenceless. So it was that the Tyranids landed in even greater numbers than before, and the fortresses soon found themselves sorely beset. Their gruesome cargo delivered, the battered Hive Ships retreated from orbit. Trusting to his Ultramarines to keep the fortresses secure, Calgar relentlessly pursued the Tyranid fleet, determined that it would not bring ruin to other worlds. Never before or since has the valour of the Ultramarines been tested as it was in the defence of the polar fortresses. The Veteran Space Marines of the 1st Company led the lightly-armed Auxilia in a tenacious defence of the fortresses, holding every wall and trench until the last possible moment before it was overrun by the Tyranid swarm. Slowly the troops withdrew ever deeper into the fortress, while making the Tyranids pay for every single yard of ground they advanced.The Titans of Legio Praetor stalked the ice fields and drove smoking furrows through the onrushing Tyranid hordes with shells and plasma. The ferocity of the swarms was unbelievable. At the northern fortress they overran the walls by using the steaming piles of their own dead for cover. Imperial Battle Titans were dragged down and ripped apart by sheer weight of numbers. The defenders' gun barrels glowed red hot and jammed in spite of the arctic cold, ammunition began to run low even though the fortress had contained stockpiles intended to last for months of siege.Yet still the defenders fought on. Lumbering scythe-armed Carnifexes tore into the defenders' bastions like living battering rams, smashing their way through metal and rockcrete walls with equal fury. The Ultramarines had to rely on heavy short-range firepower to bring down the foe, but for each Tyranid that fell, another three sprang forward to continue the fight. Lesser men were paralysed with terror as the Tyranids broke through the perimeter again and again, but the Ultramarines never despaired and never gave thought to defeat.