I couldn't remember if I put this on the boad or not, so I may repeat myself.
Man o' War shows up in Discreet Cat's pedigree 7 times from what I found. Here is the list of horses I found in Discreet Cat's pedigree that leads to Man o' War. The (m) means the horse is male and the (f) is female.
Forestry (Sire Side)
(m) Crimson Satan 9 gen. back
(f) Bolero Rose 10 gen. back
(f) Aspidistra 9 gen. back
Pretty Discreet (Dam Side)
(f) Highland Fling 8 gen. back
(f) Busanda 7 gen. back
(m) Swaps 8 gen. back
(f) Glamour 8 gen. back