The Macharian Crusade was one of the few examples in Imperial History where shit was done and done beautifully by a man with a spirit forged from unbreakable steel: the Lord Solar Macharius; Alexander the Great IN SPACE.
What makes Macharius so badass? It is because he was just a man. While the Great Crusade had the Emperor, his living demi-god sons the Primarchs and Space Marines beyond Space Marines to conquer the galaxy, Macharius had armies mostly of Imperial Guard and a few Space Marine attachments. And in the space of seven years, he and his armies conquered nearly a thousand worlds. A thousand worlds! That is around one hundred and forty-two worlds being conquered by year. This of course means he and his army were steamrolling all opposition and in a galaxy of xenos and Chaos worshipers, that says much of the man.
It was only when they reached the edge of known space leading into the Halo Zone and the edge of the Astronomican that the resolve of his men wavered. Pushed by seven years of non stop war, they had had enough and refused to go further. Macharius cried manly tears as he rallied against this, for he was having a great time but his men couldn't be persuaded further. And so ended one of the few times in the fluff when the Imperium actually behaved like the greatest power in the galaxy and took territory, rather then just flailing around getting chewed to pieces by heretics and aliens.
Of course this raises a question: if Macharius had won so many planets for the Imperium and was all ready to press on, why did the High Lords not raise another army for him or petition the Space Marines to put together a crusade group for him? It is baffling that they didn't press on their advantage. (The most probable answer is that Halo Zone, being outside the Astronomican's light, will be really hard to hold even if Macharius manages to get control over it. And going there has a pretty good chance of losing your entire army, considering that warp travel is hard there, and it's not definately known what kind of shit you might encounter.)
Anyway, after the crusade was ended, the Lord Solar Macharius died, mysteriously perishing while back on route to Terra to tell them the full results of his efforts. His end remains shrouded in mystery....which is Games Workshop's way of telling us some Inquisitor decided to off him, as most likely Macharius was actually going back to demand another army to be raised for him and they didn't want that happening.
You see, this kind of infighting and murdering of the best warleaders they have over stupid petty politics is exactly the reason why the Imperium usually doesn't get anything done.
After his death his underlings fought over the worlds he had conquered and made their own private kingdoms, the efforts of a great man undone by a bunch of chattering monkeys, an event known as the Macharian Heresy (even though Macharius himself was about as orthodox as they came). This resulted in the High Lords of Terra having to send in lots of Space Marine Chapters to get things back under control.
Order of Battle
Macharius' forces were divided into 7 Army Groups, collectively referred to as the Grand Army of Reconquest. Each army group was led by a General appointed by Macharius himself.
- The 1st Army Group of Lord Solar Macharius himself
- The 2nd Army Group of General Sejanus (Loyal)
- The 3rd Army Group of General Tarka
- The 4th Army Group of General Lysander
- The 5th Army Group of General Borgen Crassus (Loyal, Living Saint)
- The 6th Army Group of General Arrian
- The 7th Army Group of General Cyrus of Larrentine
Known Imperial Guard Regiments that took part in the Macharian Crusade include:
- Donian Imperial Guard
- 2nd Mordian Iron Guard
- 4th Catachan
- 5th Catachan
- 6th Catachan
- 12th Catachan
- 14th Catachan
- Tempestus Scion Regiments
- Terrax Guard
Known Space Marine Chapters taking part in the Crusade included:
- Death Spectres
- Doom Warriors
- Imperial Paladins
- Space Wolves
- White Scars - One Brotherhood
- Star Phantoms
- Marines Malevolent
- Lord of Light - Emperor Class Battleship, flagship in the later part of the Crusade.
- Pax Imperium - Mars Class Battle Cruiser, flagship of the Crusade but destroyed at the Battle of Charaxdis.
And then William King brought us The Macharian Crusade trilogy. These novels show a more personal look at Macharius (from the perspective of one of his honor guard) and present a different ending to the crusade itself.
The primary change to Macharius's tale was the end. Gone was the manly ending of not being able to push on. Gone was the ambiguous death en route to Terra. Now, Macharius was defeated by a traitor who was one of his greatest generals on one of the Halo worlds (Loki). When Macharius returns, he defeats the traitor, but is assassinated by an Imperial Assassin moments later (the trilogy is never quite clear on whether she is just someone who is an assassin, or if she is actually part of the Callidus temple). For ambiguous reasons, a high ranking Inquisitor wanted Macharius dead, despite being his bro for years. However, the assassin in his employ kills not only Macharius, but the Inquisitor himself, implying a much larger game was being played. For this reason, the Crusade falls to in-fighting and the Macharian Heresy begins (the years following the crusade where Macharius's top generals duked it out for control over the planets they had taken).
The trilogy also shows us how frail Macharius was starting to become near the end of the Crusade. His juvenate treatments are failing, and the High Lords want him back on Terra and in forced retirement on suspicion that he is just trying to carve out a piece of the Imperium for himself; many troops, for example, followed Macharius because he was amazing, not because he was part of the Imperium. William King allows him to go out with a bang rather than a whimper. He wins one of his greatest battles and dies with a triumphant smile on his face. Does this lessen the man's impact on the fluff? Possibly. On the one hand, the awesome fluff of him wanting to continue and go on to conquer other galaxies is gone, but on the other we have a more definitive ending for the man. Your mileage may vary, but it does present a more detailed and personal look than we have gotten, though as it is from another's perspective there is still a good amount of mystery left to Macharius.