Brother-in-arms

A loyal companion who has faced military service or severe hardship alongside another.

Reach for it when honoring solidarity formed through shared danger

He welcomed his former brother-in-arms with a long quiet embrace.

• everyday

  old service friend

  plain language should center lasting friendship after service

  not when The phrase does not convey the intensity of danger faced together.

• professional

  ally

  cooperation toward the same goal matters more than closeness

  not when An ally may be strategic, temporary, or institution-level.

• professional

  fellow soldier

  shared military role is the only verified fact

  not when Fellow soldier does not imply friendship or shared danger.

• formal

  comrade

  shared struggle and solidarity define the relationship

  not when Comrade carries political associations and need not involve military service.

• formal

  comrade-in-arms

  the military bond should be stated precisely

  not when The phrase is nearly equivalent and offers no warmer personal nuance.

• literary

  battle companion

  personal companionship during combat is central

  not when The phrase is dramatic and unsuitable for nonmilitary hardship.

• enemy
• adversary
• deserter

• former brother-in-arms

  A former brother-in-arms spoke at the memorial.

• fallen brother-in-arms

  They planted an oak for each fallen brother-in-arms.

• loyal brother-in-arms

  His loyal brother-in-arms kept writing throughout the recovery.

Brother-in-arms is gendered and military. Comrade-in-arms or a plain description may be more inclusive where identity matters.