The real story behind the Legion Workhorses of the Empire
The LEG·XV never seems to have attained such stardom as their more illustriuos colleagues like II·AVGVSTA and XX·VALERIA·VICTRIX. Being one of the battlehardened Eastern legions, their history has been obscured by the lack of archaeological findings from the former eastern-block area. The available evidence indicates that the LEGIO·XV·APOLLINARIS was constantly sent from one troubled area to another, partaking in most major campaigns in their day. As such, the Legion formed an important part of the capable and hardy elite Roman army, securing peace and wealth for the IMPERIVM·ROMANVM.
Rise of the Apollinarians
In the tumultuous years following the honourless assassination of the great statesman and general, Julius Caesar, in 44 BC,there were three contenders for the power. They were Marcus Antonius, Decimus Brutus (the dishonourable assassin) and Julius Caesars great-nephew and adoptive son, Octavianus. During these years the troops that had been loyal to Julius Caesar followed Octavianus, but he also needed to raise new troops. Among the legions raised was LEGIO·XV·APOLLINARIS, probably formed in 41 or 40 BC. During the early years of the young Empire, LEG·XV was stationed in Illuricum on the eastern coast of the Adriatick sea, today the various Balcan states. A region which was then, as well as now, a hotbed of political and ethnical strife.
Serving at LIMES·GERMANICA
In 9 AD, the Rhine frontier erupted in violence when the Germanic tribes ambushed a Roman expedition at the Teotoburg forest, destroying Varus and his three legions and conquering their SIGNA.  In an emergency effort, the German frontier was hastily strenghtened. Among the valiant Roman troops sent to prevent further millitary disasters and beat back the barbaric insurgents, was the XV·APOLLINARIS. During ten tumultuous years, the Legion was alotted inland duty along the Danube LIMES serving in PROVINCIA·PANNONIA (now Hungary and Slovenia), stationed in the cities Emona (now Ljubljana in Slovenia), and Saveria. Their mission was to replace the annihilated legions, suppress the Marcomannii revolt and restore PAX·ROMANA to the frontiers.
In 14 AD the Legion was finally given a permanent base at the former Celtic settlement Carnuntum, then a gritty, mudcaked millitary base. During the next thirty years, they transformed the makeshift fortress and the shantytown surounding it into a flowering metropol of Imperial standard, with sewers, running water, public baths, and well-planned, grid-patterened streets. Even today, walking through the old city of the former Imperial town is a half hour brisk walk! This CASTRVM was made the home base of the Apollonarians and the LEGIO·XIV·GEMINA·MARTIA·VICTRIX for years to come. Carnuntum thus became one of the largest and most important fortresses on the Danube LIMES. The city remain today, but being of such size, it was later split and is today two willages in Austria: Petronell-Carnuntum and Bad Deutsch Altenburg.
Campaigns in the East.
From their base in Carnuntum, detachments of the APOLLINARIS Legion was sent to confront invading Phartians in the years 56-63, in order to secure the Empire's eastern borders in Armenia.
In the first century, the Roman rule in ASIA·MINOR, more exact PROVINCIA·JVDEA, became troublesome. In 62 AD the Legion was ordered to break camp, and set sail for Alexandria at the south-eastern border of the Empire, possibly to secure grain shipments for Rome..
The Jewish Revolt.
In 67 AD, Titus, son of Vespasianus, marched for Judea to supress the revolt in Palestine. He marched the LEGIO·XV out of Alexandria, joined the LEGIO·V, VII and X in Ptolemais (modern Acre) and started purging the Judean towns of Zealots. Worth of mention is the town of Jotapata, where according to Josephus, handpicked units of the LEGIO·XV entered the city and opened the gates from the inside - thus winning the Legion a CORONA·MVRALIS.
The following year, the legions laid siege to Jerusalem. This siege was brilliantly executed; a fine example of Roman millitary efficiency, where the legions proved patient, disciplined and capable of technical feats unheard of in their day. The city was taken bit by bit, fighting raging from quarter to quarter. In August, the city was finally conquerd. According to Josephus, elements of the fifteenth Legion pillaged and burned the city's second temple and laid hand on the Jews' most sacred relic, the Minora and the Ark of the Covenant. In a final desecration to the temple, sacrifice was made to the Roman standards in the temple court. 
While the tenth Legion was sent to capture Masada, the battleworn LEGIO·XV went back to Alexandria where they were joined by new recruits from Cappadocia (Turkey) to replace casualties suffered in their victorious campaigns. During the spring the following year they went home to Carnuntum with their spoils of war, which they sacrificed to Mithras. This cult was then starting to become popular among Roman soldiers, and it is believed that these sacrifices started the expansion of Mithraism. The cult grew steadily during the following years, and even statesmen and emperors embraced the cult after it was promoted by Commodus during his reign from 180 to 192.
The Dacian Campaign
During the reign of the energetic Emperior Trajan, the Roman Empire reached its greatest extention, a result of the hard-fought Dacian campain. An army, assembled from the Danube legions, followed their Emperor into battle. Among them the Apollinarian Legion (or possibly a detachment thereof), fought valiantly in the 1st (101-102) and 2nd (105-106) Dacian war. The victory was one of the most outstanding in the Empire's history, and was commemorated in the unsurpassed Column of Trajan. Being a testimony to the Dacian campaign, the soldiers depicted on it might well be Legionaires and auxilia of the XV'th!
The Second CASTRVM: Satala
In the years following the Dacian campain, the Legion had but little time to celebrate their hard-earned victory. The now indispensible veteran Legion was ordered to break camp and move to a new base at the extreme eastern front of the Empire. Their guard at the LIMES·DANUBICA was tranfered to the LEGIO·XIV·GEMINA for the rest of the Roman era. The Apollinarians embarked in PROVINCIA·CAPPADOCIA (present day north-east Turkey), to enforce the PAX·ROMANA in this remote corner of the civilized world. A base was erected at Satala where local nobility paid homage to Emperior Trajan under the watchful eyes of the LEGIO·XV in 115.
It was without a doubt the great Emperor himself who established the Legion there and ordered the construction of the great CASTRA·STATIVA (permanent camp) which was to remain on Roman hands till the fifth century. A town known as Satala must have sprung up around the CASTRVM as Carnuntum had done in the Germanic wilderness almost a century earlier. In the time of Ptolemy it was already important . It still exists, now named Sadagh, a village of 500 inhabitants. From this base, the Legion probably served under Valerianus during the Persian wars in the 250's.
In 134, the Alanii tribe, with an army of heavily armoured cavalery at their disposal, threathened Roman rule in Cappadocia. Governor Flavius Arrianus took both the LEGIO·XV and the LEGIO·XII into the field and led a crushing campaign against the insurgents. The Commanders' record of the campaign is one of our most important sources of knowledge of the late Roman Army.
In 530, well after the fall of Rome herself, the fortress was still manned, and an invading Persian army was defeated under its walls. A testimony to the skills and abilities of the builders is the fact that the warlike Byzantine Emperor Justinian found the fortress still worth defending, reinforcing its fortifications in the mid 6th century. Satala finally fell to the Persians in the campgain of 607-608.
The Twilight Years: Coming of the Visigoths
Tracing the legions of the Empire through the 3rd century is increasingly difficult. Detachments from the various legions were transferred to troublespots along the LIMES, often serving for decades under other legions. A soldier might serve a full term, and never see the homebase of his Legion. The fate of the Apollinarians might be guessed at, though.
During the reign of Emperior Valensius, the worst millitary disaster in the history of Rome occured. In 376 AD, Visigoths fleeing the Huns sought sanctuary on the roman side of the Danube. They were to prove ungrateful guests. Being treated badly, they rebelled against their host, using the latest in millitary technology: The stirrup. With emergency speed the Eastern Army was assembled. In 378 AD, Visigoth cavalry and the Eastern Roman Army met near Adrianopol (now Edirna in European Turkey). Unable to counter the swift lancewielding cavalry, the footsoldiers of the Empire was eventually packed so tightly they could not raise their arms. The battle raged the whole day. In torchlight, the fight turned into a massacre.
That massacre was the end of the Army of the East. With the loss of the backbone of her forces, the Empire was powerless to turn back the flood of barbaric hordes. Chaos reigned unchecked for a generation. Visigoths and Vandals even sacked Rome itself. Though order was briefly restored by Diecletorian, the Empire never recovered from the loss of the battle-hardened Eastern legions. In 395 the Empire was split, and 15 years later Rome itself fell to the Goths. The swift fall of Rome following the defeat is perhaps a tribute to the fighting prowess of the Eastern legions, having held back the tide of chaos for so long.
Did the XV'th fall at Adrianopol? In the tumultious years leading up to the battle, we loose track of the Legion. Still, Satala seemed to have been manned by imperial forces as late as 425 AD. Perhaps the LEGIO·XV·APOLLINARIS died on barbarian lances at Adrianopol, defending the Empire they were raised to serve. Perhaps they held out, vigilantly on guard against the enemies of Rome until the very end of the Empire, or dissolving into the Byzantine forces. Whatever the end, the Apollinarians served their Emperors for almost half a millennium, epitomizing the loyalty, bravery and millitary proficiency of the Roman Legionnaire.
 Current scientific debate argues on whether the city of Ebona existed
from earlier or was founded by LEGIO·XV·APOLLINARIS, wintering there
before their transferrence to Carnuntum.
 Scientists argue as to the city's year of foundation. Prior to
roman conquest, it was possibly the seat of a celtic chieftain or
king. In 9 AD the city was occupied by Augustus to serve as a basecamp
against the marcomanii. However, scientists have dated the origin of
the city (as opposed to the camp) to the years 35-40 AD.