The Special Military Forces is the Hellsing Organization's own private army that was funded and formed by the Hellsing family to serve as their security force.
History
Under the command of Sir Integra, over one hundred able-bodied men are well versed in the art of military combat with creatures mostly unbeknownst to the innocent masses. These fearless soldiers stand to protect England from the threats of the damned and lose their lives for the cause. In the manga and OVA series their role appears limited to simply guarding Hellsing House, however the television anime greatly expanded their role, having the men actively attending missions to suppress occult threats alongside Seras.
In the Manga & OVA
During the attack on the Hellsing manor led by the Valentine Brothers, these soldiers tried to fend off the Ghoul army but despite their best efforts were all killed in the process. The remaining soldiers tried to ambush Luke, but he quickly killed them using his vampiric abilities. The fallen soldiers were then reanimated into ghouls, but Seras was able to kill most of them. Sir Hugh Irons later orders Integra to put the remaining undead soldiers out of their misery herself as due to her lack of preparation for such an attack resulted in their deaths. Sir Irons gives Integra a revolver and she executes her undead men one by one, they were all given a proper burial. Out of all the one hundred personal, only ten survived, eight of them were assigned elsewhere during the attack, while the other two being Walter and Integra.
In the Anime
Unlike in both the manga and the OVA, the Military force instead of mostly serving as security also serve as a vampire extermination task force, they are mobilized whenever there are vampire activities around London, they are led by Peter Fargason. Over the course of the anime, they suffer casualties caused by Alexander Anderson, the Ghoul army, and Incognito's vampirized SAS forces.