Hier die Quellen für diejenigen die dies vielleicht übersehen haben.
Polygon
The first was that there were a lot of units that were just additional equipment for your units. It might be a battering ram or a siege tower or an anti-aircraft gun or an anti-tank gun. In Civ 5 those were all special units that took up a whole dedicated tile. In Civ 6, we call them support units. They can stack with other military units without you having to worry about managing them on a tile by themselves.Achtung Spoiler:
IGN Australia
Second, the concept of grouping into formations. Calling it a long-requested feature, Shirk says you’ll be able to link two units (one military and one civilian) together and will be able to move them around together with a single movement command. “That’s really nice with civilian units, as you can escort settlers or builders or missionaries around the map.”Achtung Spoiler:
Dies macht natürlich schon viel aus, und wird auch mehr Platz sparen auf der Karte. Dazu kommt denn ja auch noch das man gleiche Einheiten zu Korps und später zu Armeen zusammenfügen kann.
Polygon
"The other part was, we found that once you got your production going in the middle to late part of the game, sometimes you could have lots of units of a certain type. We felt like it was a more realistic part of military history at that point in time if you could concentrate your forces better and achieve what we called corps or armies, where you take two or three units and stack them together.
"That unit is going to have a lot more punch, probably have the ability to drive a hole right through the enemy battle line. That’s how that system works. Now, once you link two units into a corps, they’re individual units, but at that point they’ve been upgraded. You want to keep them in that fashion if possible. (...)"
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IGN Australia
Finally, to minimize late-game unit bloat, Firaxis has created Corps and Armies: two or three of the same unit type (a Rifleman, for instance) combined into a single, more powerful version of that same unit. A Rifleman Corps unit would be roughly 40% more powerful than an individual, which means they’re less potent than the two component Riflemen would be by themselves, but together they’re more survivable and potent in a single attack. Having the option to create Corps (unlocked in the Napoleonic era), and then later add a third unit to create an Army (unlocked around 100 years later), is designed to open up new tactics and reduce overcrowding on the map.
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Edit: Da ich momentan Zeit habe, habe ich mich an grobe deutsche Übersetzungen der einzelnen Textzeilen versucht und diese in Spoiler gesteckt.