Amid pronounced anxieties that “new” forms of warcraft (technological, psychological, guerrilla, nuclear) would obviate manly soldiery in the post–World War II period, Brazilian, French, and US military theorists shared a discursive space in which they worked out these fears via the invention of counterinsurgency doctrine. In so doing, they both demonized guerrilla warfare as an unprecedented innovation of nefarious communists and imagined an idealized counterguerrilla or counterinsurgent warrior who must outpace the guerrillas’ putatively formidable masculinity. This essay traces the ideological contours of the transnational alliance of military theorists that collaborated in conceptualizing counterinsurgency as a formal, and now central, stratagem. Key to the cohesion of this alliance was a vision of remasculinization as the bulwark of Western defense. Hashed out in trans-Atlantic conversations, such remasculinization took the particular form of lack of restraint—laying the groundwork for indiscriminate violence, unmoored even from the pretense of rules of engagement.