Approx. 172 A.D. - The 'Thundering Legion' Incident
Note the upturned shields - to catch water!
This incident has been obscured somewhat through time by the affects of both Christians and pagans relating their story to their own particular audiences, but if you read all the accounts you can find, it pretty soon seems very likely that the Christian account must take the day.
The reason that I ended up leaning this way is that there really was an unusual event - both Christian and pagan sources agree. It went a certain way, and a divine hand was readily apparent in the events of that particular day, to all who wrote about it. The Christian sources give Christ the glory for it. The pagan sources either attribute it to Roman gods, or to the power of a certain Egyptian sorcorer that accompanied this Roman army.
But what seems like the telling detail is that a Legion composed of largely Christians was renamed the Thundering Legion, by Aurelius, the Roman Commander, because of the event. Secondly - call me partial - I know quite well that neither the Roman's false gods nor the Egyptian's can do anything of much or any consequence!
In approximately 172 A.D. Marcus Aurelius was leading a Roman military expedition against peoples called the Quadi and the Marcomani in geographical areas later known as Bohemia and Moravia. It was summer, and he had gotten his army into a serious pickel - in fact their very survival was looking doubtful. They were hemmed in in some rough terrain, surrounded by a foreign army which greatly out numbered them.
The Romans were quite adept at fighting superior forces when they had to, but their problem on this day was that their paths to drinking water were all easily denied them by the enemy due to some combination of the geography and the enemy's numerical superiority. They were standing in formation, not daring to relax, and the harsh sun and the especially hot day were roasting them to death. They were in desperate need of water, growing weaker and more vulnerable, but too surrounded to go get it.
The enemy, meanwhile, had access to water, was in a much more comfortable position, and was happily waiting. They were quite aware that the intense heat was doing their work for them. When they finally attacked they hoped to face as weak a foe as possible.
One of Aurelius's officers came to him with a thought: He told his commander that one of the Legions - the 12th - was composed largely of Christians from the area of Cappadocia. It was said, he reminded his commander, that Christians could obtain or accomplish many remarkable things through prayer to their God named Jesus.
Needy as he was, Aurelius passed word requesting the soldiers of the 12th Legion should pray to their God. Standing in their ranks, the men of the Roman 12th complied. They began to pray for aid from Jesus.
As they prayed, clouds began to form overhead with a rapidness that was reported to be unusual to all observers, and suddenly they had become heavy and black enough that the rain began to fall, and copiously. The enemy realized that their advantage was evaporating (or rather drowning), and they attacked. The Romans for their part began to gulp the heaven sent water from shields, helmets, and cupped hands as best they could while simultaneously bracing for the attack that they saw coming. But hail and lightening fell upon the attacking forces, terrifying their animals and the men. It seemed that only they, and not the Romans, were singled out by the weather.
The battle was soon won for and by the Romans (well, reportedly by prayer to Jesus, actually) and the attacking forces surrendered in the face of this apparent non-neutrality of the heavens themselves. In the aftermath, it is said that the largely Christian Roman 12th Legion won a new name - 'the Thundering Legion'. And by at least some accounts a proclamation was made that Christians would not be persecuted in the Roman Empire. But if such a proclamation was made, it certainly wasn't honored for long.
Incidents like this would certainly cause all of the rescued soldiers to take a new look at who this Jesus was. It's evident that even in the 'Acts of the Apostles' time frame, and at the crucifixion of Jesus himself, God was making inroads into the Roman culture, preparing Roman hearts and minds to hear the gospel. And in all likelihood the Quadi and the Marcomani that they fought that day later inquired into the events. Perhaps they too became curious about this Jesus. The Lord - He is God! The Lord - He is God! Doesn't it hearken back to the times of Elijah and Elisha when fire fell from heaven and burnt up the offering, the wood, and even the water that God's enemies had poured upon it? Nothing is too hard for the Lord!