After , Big Boss became increasingly frustrated with the direction that Zero was taking the Patriots, so he left the group and began preparations to oppose it. Big Boss later formed the (French for "Soldiers Without Borders"), combining the best aspects of a state army and a special forces unit.

The MSF were hired to repel the from in , dispatching its forces into several warzones for income to increase its numbers; as well as maintaining supplies for its personnel. As the MSF's grew in size and power, it even gained nuclear capability. ( had referred to it as the 7th nuclear power at the time.) While still considered a group of renegades, Big Boss thought that MSF was quickly becoming his personal "Outer Heaven": a soldier's paradise existing free of any one global power's political control; or a home for those shunned amidst a global cold war. After defeating the nuclear-armed AI weapon , MSF successfully subdued an internal rebellion instigated by – a.k.a. Zero – in which was hijacked.

After awakening at a hospital in Cyprus in 1984, Big Boss was reacquainted with fellow Patriot founder Ocelot. There, Ocelot (under Zero's direction) suggested that he use a body double, , to distract XOF and the world from the true Big Boss; yet at the same time, expand his legend. Venom Snake would later be rescued by Ocelot, and go to to rescue Kazuhira Miller from Soviet forces. Snake succeeded in rescuing Miller; and the two vowed to have their revenge against Cipher for everything they had lost and rebuild, with Venom Snake already declaring himself a fallen demon. It was during this time period that he reorganized what remained of MSF into a unit known as the : a group willing to perform unsavory jobs for whatever client needed it. Through it, he expanded his Outer Heaven concept from one which merely takes in soldiers without a homeland, to a full-on and infamous mercenary force. During these events, it was revealed that the real Big Boss had already been establishing the "real" Outer Heaven in South Africa. While it is not explicitly stated, it can be assumed that Diamond Dogs were absorbed into Outer Heaven.

leader soldier vehicles and metal gears 

big boss or snake 

ocelot 

miller