In Civilization VI, units in hostile territory can heal only 5 HP per turn, which is very little when exposed to continuous fire. Here's where the Medic comes in - thanks to its services unit healing becomes significantly better, which may mean the difference between a successful siege and a defeat of your army. And don't think that just because your Artillery can shoot a city from afar, your other units will be completely safe - the enemy has tons of other means of harming an invading army in the Modern Era.
It takes a brave person to rush onto a battlefield unarmed, especially to provide trauma care in the front lines. Although “protected” by age-old edicts and the Geneva Convention, being a military medic is not conducive to good health. Surgeon Dominique Larrey developed the first ambulances volantes (“flying ambulance”) – mobile field hospitals – for Napoleon’s Grande Armée; he also recruited and trained volunteers to aid the wounded and carry them back to the field hospitals. Not only did it improve the survival rate – which certainly boosted morale – but it insured that at least some would survive to fight again. During the American Civil War, Major Jon Letterman of the U.S. Army of the Potomac not only developed and standardized new equipment for saving lives (this in an age when amputation was the usual cure), but expanded the medic’s role to dealing with diseases and other ills of the draftees. Today, army medics and naval corpsmen are integral to every nation’s military.