He did not. The first race in the Triple Crown is the Kentucky Derby. The Derby is restricted to three year olds. Seabiscuit was a late bloomer, when he was three he was lame and cranky due to overwork and excessive training. To compete at that level he would have had to be winning consistantly against some very tough competition.
No, Seabiscuit never raced in any of the Triple crown races.
Winning Colors won the Kentucky Derby in 1988.
In 1948.
1978
Not the US Triple Crown. But he did win the UK Triple Crown.
1966
1930
1977. When he died in 2002 he was the last living Triple Crown winner.
This can't be answered unless you give a list of horses.
Secretariat won the triple crown in 1973. He was the 9th horse to do so in 25 years.
Bahram won in 1935 :)
A horse rider can win the Triple Crown by having their horse win three prestigious horse races: the Kentucky Derby, the Preakness Stakes, and the Belmont Stakes in the same year.