/ˈrɪəɡɑːrd/
[noun] A group of soldiers who protect the back of an army as it moves or retreats. More broadly, it describes a group of people who defend something old or traditional against change.
The word 'rearguard' was born on medieval battlefields where the soldiers at the back held the most dangerous position of all.
To understand 'rearguard', you need to picture the anatomy of a medieval army on the move. Soldiers did not simply march in a single mass — they were organised into three distinct sections: the vanguard at the front, the main body in the middle, and the rearguard at the back. Of these three positions, the rearguard was often the most dangerous. When an army retreated, it was the soldiers at the rear who faced the enemy's pursuing forces, absorbing blows so that their comrades could escape. The word carries this history of sacrifice and stubborn resistance in its very bones.
The first half of the word, 'rear', travels a long road before reaching English. It comes from the Old French word 'riere', meaning 'behind' or 'back', which itself descended from the Latin 'retro', meaning 'backwards' or 'behind'. Latin 'retro' also gives us words like 'retrograde' (moving backwards), 'retrospect' (looking back at the past), and 'retroactive' (applying to things that happened before). The 'rear' of a building, the 'rear' of a queue, even the informal use of 'rear' as a polite word for the human backside — all trace back through Old French 'riere' to this same Latin root.
The second half, 'guard', has an equally interesting journey. It comes from the Old French word 'garde', meaning 'protection' or 'watching over', which derived from the Frankish word 'warda', meaning 'watching' or 'guarding'. This Frankish root is related to the Old High German 'warten', meaning 'to watch', and connects to the same Germanic family that gives English 'ward', 'warden', and 'wardrobe' (originally a room where you 'guarded' your robes). The French and Germanic streams of the same root flowed into English side by side, which is why English has both 'guard' (from Old French 'garde') and 'ward' (from the older Germanic form directly).
The compound 'rearguard' entered English in the 15th century, borrowed directly from the Old French 'rieregarde', where 'riere' (behind) combined with 'garde' (guard) to name this crucial military formation. English-speaking soldiers and chroniclers of medieval warfare adopted it wholesale, and the word appears in accounts of battles and campaigns throughout the late medieval and early modern periods. For centuries it remained primarily a military term, describing a concrete tactical reality.
The word's great leap came when it moved beyond the battlefield into everyday language. By the 19th century, writers and thinkers began using 'rearguard' figuratively, particularly in the phrase 'rearguard action' — a phrase that means fighting a losing battle while trying to slow down defeat. This metaphor proved irresistible. Politicians fight rearguard actions against reform. Critics wage rearguard actions against new artistic movements. Scientists sometimes mount rearguard defences of older theories. The phrase captures something deeply human: the courage, stubbornness, or simple desperation of those who refuse to give up even when the tide has turned against them.
What makes 'rearguard' so enduring is the moral ambiguity built into it. A rearguard action can be heroic — a small band of soldiers holding a pass so thousands can escape — or it can be futile and even misguided, the last defence of something that deserves to be left behind. The word does not judge. It simply describes those who stand at the back, facing what is coming, while everyone else moves forward.