General Warfield was affiliated with operation Shadow Blade, converting Ghosts to Spectres. This was to be a main focus in Starcraft: Ghost, but were later highlighted in a mission in Starcraft II: Wings of Liberty where Spectre leader Gabriel Tosh takes on the ghost Nova to free a group of rogue spectres.
Starcraft II: Wings of Liberty
Warfield accompanied Valerian Mengsk to the planet of Char for an assault on Sarah Kerrigan's stronghold. He led a full frontal attack that caused the Dominion forces heavy losses. Warfield himself was almost killed by a Hydralisk before he was saved by Jim Raynor, but he had his right arm amputated to save himself from the poison in the Hydralisk's spines, and handed command over to Raynor while he recovered. Before the final battle, Horace returned and had a robotic arm attached to his armor. This attachment is capable of retracting the hand and producing a massive hand cannon.
General Warfield's portrait is be unlocked for use in your Battle.net online profile upon completion of all 29 missions (including the hidden mission and the 3 choice missions) in the Wings of Liberty campaign on Normal Difficulty,