Coalitions among individuals and between groups, which have had critical evolutionary benefits for humans, play an important role in contemporary life. One key element of the processes of assessing potential allies is how they may contribute to the perceived physical formidability – fighting ability or the capacity to inflict costs on others – of the alliance. In three studies, focused for the first time on intergroup coalitions, we investigated how qualities of the groups such as status (social prestige) and the relationship between them influence the perceived physical formidability of a coalition (i.e., European Union, EU). Study 1 found that the inclusion of a group with higher or similar (but not lower) status increased the perceived formidability of the EU. Studies 2 and 3 showed that learning that ingroup members recategorized a low‐status group within a common‐group identity increased the perceived formidability of the EU including that group, compared with the conditions in which either outgroup members recategorized or no information was provided. Study 3 also revealed mediation by fusion – a visceral connection – with outgroup members, which has been relatively unexplored. Taken together, these studies reveal that both, status and social identity processes, may significantly affect the estimations of coalitional formidability.