The emperor Aurelian's army (270-275) had to have been an incredibly disciplined and accomplished fighting force. The source material is so limited that we cannot know Aurelian's campaigns in great detail, but a glance suggests the brilliance of his army. In a time when armies made and broke emperors on the reg, Aurelian maintained military loyalty for five years (long for the period), during which he did the following:
1. Defeated his rival Quintillus (270).
2. Defeated a Iuthungian incursion into Raetia (270).
3. Defeated a Vandal incursion into Pannonia (270/1).
4. Defeated a Iuthungian invasion of Italy, winning three battles (271).
5. Put down a rebellion in Rome (271).
6. Defeated the usurpers Domitianus in Narbonese Gaul and Marcellinus in Dalmatia (271) [although these two may have been defeated by loyal armies under subordinates rather than the field army of Aurelian]
7. Launched a punitive expedition across the Danube against the Goths (272)
8. Defeated the Palmyrene Empire of Zenobia, with major victories won at Tyana, Immae, Daphne, Emesa and Palmyra (272)
9. Defeated the Carpi (273)
10. Defeated a second Palmyrene rebellion, with one detachment or loyal army putting down a related rebellion in Egypt (273)
11. Defeated the Gallic Empire of Tetricus (supposedly Tetricus betrayed his own army to Aurelian, recognizing that he had little chance against Aurelian and not trusting in the loyalty of his own soldiers) (274)
12. Dealt with unrest in Gaul (275)
12. Defeated a German incursion into Raetia (275)
13. Marched his army towards Persia (275)
Aurelian was assassinated in Thrace en route to Persia because of a conspiracy involving some of his secretaries and officers. Nevertheless, it is telling that the assassins fled to Asia Minor, and that the army did not organise a replacement, but deferred to the senate to appoint their next emperor. This was completely at odds with practice at the time. It shows that the army was blindsided by Aurelian's death and had not been anticipating his replacement in any meaningful way. This seems telling, considering that between 235 and 285 numerous emperors were appointed and replaced by the army. The overall picture we get is an army that was incredibly mobile, successful and loyal to its emperor in spite of the third-century zeitgeist.