Charles Irwin appears in the second chapter of this animal biography when he offers Smith a job on his road to becoming the trainer of Seabiscuit. From everything we are told, we can easily see how Charles Irwin was a larger than life character, in every sense of the word. Notice how the author describes him in the following quote:

Irwin was a colossus, in form and personality. His weight, thanks to a glandular disorder and 50-pound tumours, swung from a comparatively petite 400 pounds to 540 pounds, packed mostly in a monstrous quaking belly that won him the nickname "Ten Ton" Irwin.

He had two business that involved horses, and employed Smith to be a foreman and an assistant trainer. Although this was very hard for Smith, as Irwin often insisted on running horses to exhaustion and focused on artificialities in his presentation, Irwin's importance in this story is the way in which he gave a job to Smith that enabled him to think and develop systems to ensure that a horse left the line as quickly as possible to give them the best chance of winning a race. This became crucial for his training methods with Seabiscuit.