Till was a poor but brilliant blacksmith working in King's Landing. His fascination with all things vehicle had grown since he first saw one. His genius was in all things mechanical, and in his spare time, he worked to improve the vehicle system. He had watched as a 3- or 4-car vehicle was loaded down, and sand had to be thrown on the tracks to give it enough grip to begin moving forward. It occurred to him that adding weight to the front power car would help with this problem. He had no understanding of the magics involved with the wind power that drove the vehicles. His mind worked feverishly on how to power this vehicle with any other method.
One day, he was at lunch in a local cafe when a kettle began to boil. He watched closely as the steam began to pour out of its spout. It reached such a furious rate of expulsion that the kettle began to whistle. Something clicked into place in his mind, and he began to feverishly conjure ways that steam could be used to power a vehicle. Over several months, he developed a piston-driven steam engine. It took him some time to produce a 4-piston setup that could hold the full pressure of the steam and deliver it to a drive shaft.
One day, as he was doing some testing, a knock came at his workshop door. It was Bran, his liege, and several maesters. Till bowed low, wondering what this was all about. Bran said, "A little birdy told me about your advancements in the vehicular system. Care to demonstrate for us?" Till happily obliged, and the small group watched in fascination as steam built up, and a lever was turned, allowing it to push the pistons up and down. Bran studied the revolutions of the 'shaft' through which the power was being delivered. He said, "How do you convert this turning of this shaft into power at the wheels?" Till showed them some mock-ups he had devised, a flywheel with a strap attached that would turn a wheel.
Bran laughed heartily, saying, "Truly, you are a genius! Why don't you come to work in a new workshop with lots of other mechanical geniuses to develop this idea of yours? You will be quite well paid for your efforts, young man." Till was overjoyed at the thought of being rich and having everything he needed to make this advancement happen. Till smiled with tears in his eyes, saying, "Yes, my liege, yes!"
About the time the invasion began, the tested prototype of the new mechanical 'engine' was brought out on the tracks north. The engine weighed about 5 times as much as a wind-powered front car. It had a water tank that would run the engine at full speed for about 4 hours before needing to be refilled. 10 troop cars and 3 freight cars were attached to it, three times as many as a wind-powered vehicle could carry. Coke had been substituted for the woodfire Till had begun with; the coke burned so much hotter and gave the engine better speed. Another car had to be added to carry all the coke needed to run the furnace boiler.
Bran showed up at the initial test run, saying, "Some changes have been made. A Zonian invasion force has reached the Saltspear coast, and 600 troops, along with their gear and food, are being loaded as we speak. The spur west from the neck has been finished in time, and a wagon full of water will meet you at the neck roundhouse. We need the troops there now!" Till started to go into the engine, and Bran stopped him, saying, "We can't risk losing your genius, Till." Till sputtered, "I have been working on this for 2 years, my liege, surely you won't stop me from its maiden voyage?" Bran coughed, allowing him to enter the engine. Adding, "Be safe, young man, we need you back here quickly."
As the engine came to a full boil, a steam whistle sounded, and the long group of cars began moving slowly. Bran chuckled happily as it built up speed moving north, saying, "Look at that long train of cars moving so quickly." The name stuck, and the vehicles became trains ever after.
It took seven hours to make the 800+ miles to the neck roundhouse. They had to stop once at a stream to refill the boiler tank. They took on water at the roundhouse and made their way to Barrowton in 4 1/2 hours. At the small 'train' station at Barrowton, they unloaded the troops and their gear. A soldier approached Till and asked if they would be ok with taking a load of wounded and some prisoners to Brandon's Rest. The man stated, "Most of these wounded won't survive the long journey back to King's Landing." Till agreed to it. So the wounded and some prisoners and their guards were loaded aboard. They took what coke the town could spare and began the journey farther north.
Some lightly wounded soldiers climbed into the engine and began to describe the pitched battle that was going on on the coast south of Barrowton. Roughly 6 thousand Zonian troops were fighting their way north off the coast against 4000 Westeros troops. The soldier said, "That 600 you just brought may well sway the battle. We have the high ground against them, but it is nip and tuck all the way."