Conversation so far:
When did seabiscuit get into racing?
Seabiscuit was bred and born to be a racehorse. As a two-year-old, Seabiscuit raced 35 times.
Did Seabiscuit win his first races?
Seabiscuit failed to win his first 17 races, usually finishing back in the field.
When did Seabiscuit start winning races?
Seabiscuit began to gain attention after winning two races at Narragansett Park and setting a new track record in the second - a Claiming Stakes race.

Question: Was he a well-known race horse?
Self-contained rewrite: Was Seabiscuit a well-known race horse?