Supposedly, Gaius Cassius was a Roman Centurion stationed in Jerusalem during the life of Jesus. He developed partially-blinding cataracts, with the consequence that Pontius Pilate relieved him of normal duties and assigned him to the task of spying, viewed as a kind of "desk duty."
Simply because Jesus attracted crowds, Gaius, nicknamed "Longinus," began to follow and spy on Jesus, and make reports on him.
Longinus quickly came to respect, and ultimately to love, Jesus. His reports on Jesus were favorable. Pilate was disturbed by the attitude of Longinus toward this "rabble-rouser."
When the day came when Pilate surrendered to political pressure and ordered the execution of Jesus, he decided to test Longinus' loyalty, by placing him in charge of the death march and crucifixion.
Trapped by duty, Longinus did what he could to ease Jesus' execution. He ordered Simon of Cyrene to carry the cross for part of the way of the cross. At the Place of the Skull, after Longinus suffered terribly as he watched Jesus get nailed to His cross, something else happened.
When soldiers were sent from Jerusalem with ladders and hammers, Longinus immediately understood precisely what was occurring.
When people were crucified by the Romans, one of the causes of death was suffocation. The weight of the body hanging by the arms from the cross caused the lungs to be squeezed. Crucifixion victims would therefore try to stand on the cross, to relieve the pressure on the lungs, to enable them to breathe. Crucifixion victims would rise, breathe, sink, suffocate, rise, breathe, sink, suffocate, up and down, ep and down, sometimes for days, until their legs gave out, and they they suffocated. The Romans would sometimes shorten the executions by breaking the legs of the crucified, to make it impossible for them to stand, bringing about immediate suffocation.
But, here the hammers and ladders were being brought to the crosses way too early. While spying on Jesus, Longinus had become very familiar with the prophecies in Judaism about a Messiah to come -- among other things that not a bone in his body would be broken. Longinus was certain that someone was anxious to put an immediate end to speculation that Jesus was this "Messiah" by breaking his bones in the guise of hastening Jesus' death by breaking His legs. People would say, "He can't have been the Messiah -- See? Bones were broken!"
This idea filled Longinus with rage. He thought something like, "What???!!! What???!!! Hasn't this perfectly innocent man been abused enough???!!! Now they are going to beat his legs with hammers just to prove that he is not this 'Messiah'!!! I can't stand it!!!"
As the men began their work with the two thieves, to hide their special interest in breaking Christ's legs, Longinus saw to his surprise that Christ was dead already. Yet, he saw the men moving to break Christ's legs, anyway. "They are going to abuse the man's corpse for their stupid political reasons!!!"
Overcome with anger and zeal, Longinus jumped on his horse, spurred the horse over to a soldier holding a spear, seized the spear, spurred his horse over to Christ's cross, and rammed the spear into Christ's side, yelling something like the ancient Latin version of, "There!!! See, you morons???!!! He's already dead!!! No need to break his legs!!!"
And that is why John's gospel says that instead of having His legs broken, Christ was stabbed in the side!!! It was an act of love!!!
When the tip of Longinus' spear pierced Christ's side, the accumulation of lymph and blood filling Christ's lungs, generated by the siezing caused by His savage scourging hours earlier, exploded outward and flooded down the spear and down Longinus' arm, and splashed into his eyes.
His cataracts fell off.
Suddenly, his vision was perfect.
To this day, the head of the spear piercing Christ's side can be found in a museum, the Hofburg, in Austria.
And in Densus, Romania, we have an ancient Christian mausoleum converted into a church. The mausoleum's Latin inscription reveals that the one buried inside is the Roman centurion Longinus.