|It wasn't until later that someone pointed out that|
the Ultramarines use the colors of my alma mater
I've long envied the Imperial Guard's Heavy Support options (I've since become irrationally fond of the Leman Russ design) and saw the Auxilia as an interesting way to bring IG weaponry to the table in support of the Ultramarines. The chance to add more variety to my army in the form of less costly support troops and a greater choice of vehicles was also appealing. However, under 5th Edition I was reluctant to start an Auxilia force since there was no official way to incorporate allied armies and I didn't necessarily want to build a standalone IG army.
Then 6th Edition came along and GW gave us an official way to add allies to our main armies. After working through a few potential arrangements (some with the Marines as the primary detachment, some with the Auxilia as the main force), I realized that I could pretty easily assemble some competitive lists featuring the Ultramarines and their Auxilia.
Since there aren't any official description of what Auxilia troops look like, I'm going to have to figure out how to build and paint such a force. Some sources indicate that Cadian gear is considered the standard for Imperial Guard regiments. Given the Ultramarines' obsession with standardization and the fact that the Ultramar Auxilia is supposed to be able to either fight alongside the Imperial Guard or to be incorporated into it as needed, I think it can be assumed that Auxilia troops would look similar to Cadian shock troops (this would be a budget-friendly decision given that Cadian figures are GW's standard IG models). Since blue seems to be the representative color for the Ultramar System, I would probably paint the Auxilia's helmets and flak armor Macragge Blue. For contrast, I'll probably paint the cloth portions of the uniform either gray or a light khaki. For diversity, I've considered painting each trooper's right shoulder pad with colors representing his homeworld. The left shoulder pad could have the number of his squad. I toyed with the idea of painting the inverted omega on the troopers, but decided that the symbol should be reserved for the Ultramarines themselves, although I may paint a small emblem on the Auxilia's veteran sergeants and officers as a mark of honor.
|Does it come in gray? Perhaps with some blue highlights?|
As for the vehicles, they would be the stock IG variants, although a few details may be different. For example, frequently replaced add-on items such as smoke launchers and searchlights might be shared between Ultramarine and Auxilia vehicles. The Auxilia's vehicles should sport at least some of Ultramar's trademark color, although it just wouldn't seem right to me for their tanks to be entirely blue. The privilege of painting their vehicles entirely in the color of Ultramar (as well as the utter disdain for the concept of camouflage) belongs to the Ultramarines. Thus, the Auxilia's vehicles will probably be painted in shades of gray with a few blue markings. Again, as with the troopers, the vehicles would forgo the use of the inverted omega. I might just go with a simple "ULTRA" on their hulls.
Unfortunately, I've gotten pretty excited about building an Auxilia army, but I still have a huge number of unbuilt Space Marine models. Curse my slow building pace.