Ultimately, all successful games of Colonization will end in combat, as your fledgling colonies declare independence and fight to separate themselves from the European continent. Thus, you must maintain a sizeable army, potentially consisting of soldiers, cannons, and dragoons, and, if possible, a navy as well. Keep in mind that the Royal Expeditionary Force (REF), the term given to the soldiers sent by the King in Europe, can grow in size throughout the game, and so what may have been an adequate defense years ago could no longer ensure victory. The REF, however, lands at your shores in waves, making it more manageable to handle.
Units can be acquired in a variety of ways: the most straightforward, but also the most expensive, involves buying units directly from Europe for an amount of gold. While these troops may be more experienced, they also require an increasing amount of gold: that is, the second cannon you purchase costs more than the first. On the other hand, you can create units in the homeland at the cost of no gold, but rather resources. You need a stockpile of Guns (which can be manufactured from Tools in an Armory) to equip ordinary colonists into soldiers. Dragoons can also be created from Guns as well as Horses, offering a mounted alternative.
Note: The 41 units available in Colonization are detailed below, with their information accurate as of the game version 1.00.
| Image | Name | Strength | Movement | Requires | Abilities |
 | Artillery | 4 | 1 | 40 Tools 200 Hammers Armory / Magazine / Arsenal | Replaces Cannon Doesn’t receive defensive bonuses +150% settlement attack +50% settlement defense Can bombard settlement defense (-20%/turn) |
 | Cannon | 3 | 1 | 40 Tools 200 HammersArmory / Magazine / Arsenal | Doesn’t receive defensive bonuses +100% settlement attack +50% settlement defense Can bombard settlement defense (-12%/turn) Replaced by Artillery |
 | Caravel | 3 | 3 | 30 Tools 100 HammersDrydock | Cargo space: 2 Can only defend Chance to escape to Drydock or Shipyard after losing a battle |
 | Converted Native | 0 | 1 | – | Can only defend Can found a new settlement -1 production of Cloth, Coats, Rum, Cigars, Tools, Guns, Hammers, Liberty Bells, Crosses, Education +1 production of Food, Lumber, Silver, Cotton, Fur, Sugar, Tobacco, Ore, Horses |
 | Elder Statesman | 0 | 1 | – | Can found a new settlement +100% production of Liberty Bells |
 | Expert Cotton Planter | 0 | 1 | – | Can found a new settlement +100% production of Cotton |
 | Expert Farmer | 0 | 1 | – | Can found a new settlement +3 production of food on land +2 food from bonus resources |
 | Expert Fisherman | 0 | 1 | – | Can found a new settlement +3 production of food on water +2 food from bonus resources |
 | Expert Lumberjack | 0 | 1 | – | Can found a new settlement +100% production of lumber |
 | Expert Ore Miner | 0 | 1 | – | Can found a new settlement +100% production of ore |
 | Expert Silver Miner | 0 | 1 | – | Can found a new settlement +100% production of silver |
 | Expert Sugar Planter | 0 | 1 | – | Can found a new settlement +100% production of sugar |
 | Expert Tobacco Planter | 0 | 1 | – | Can found a new settlement +100% production of tobacco |
 | Expert Trapper | 0 | 1 | – | Can found a new settlement +100% production of fur |
 | Firebrand Preacher | 0 | 1 | – | Can found a new settlement +100% production of crosses |
 | Free Colonist | 0 | 1 | – | Can found a new settlement Replaced by Native |
 | Frigate | 8 | 5 | 200 Tools 200 Muskets 300 HammersShipyard | Can bombard settlement defense (-8%/turn) |
 | Galleon | 5 | 3 | 100 Tools 300 HammersDrydock | Cargo space: 6 Can only defend |
 | Great General | 0 | 2 | – | Can provide a one time 20 experience to units in the same tile. Grants free upgrades to the unit it attaches to. |
 | Hardy Pioneer | 0 | 1 | – | Can found a new settlement Improves the land 100% faster |
 | Indentured Servant | 0 | 1 | – | Can found a new settlement -1 production of Cloth, Coats, Rum, Cigars, Tools, Guns, Hammers, Liberty Bells, Crosses, Education |
 | Jesuit Missionary | 0 | 1 | – | Can found a new settlement Missions are 50% more effective |
 | Man-o-War | 12 | 4 | 300 Tools 300 Muskets 400 Hammers | Replaces Ship of the Line Cargo space: 4 +50% vs.Frigate Can bombard settlement defense (-12%/turn) |
 | Master Blacksmith | 0 | 1 | – | Can found a new settlement +100% production of tools |
 | Master Carpenter | 0 | 1 | – | Can found a new settlement+100% production of hammer |
 | Master Distiller | 0 | 1 | – | Can found a new settlement+100% production of rums |
 | Master Fur Trader | 0 | 1 | – | Can found a new settlement+100% production of coats |
 | Master Gunsmith | 0 | 1 | – | Can found a new settlement+100% production of guns |
 | Master Rancher | 0 | 1 | – | Can found a new settlement+100% production of horses |
 | Master Tobacconist | 0 | 1 | – | Can found a new settlement+100% production of cigars |
 | Master Weaver | 0 | 1 | – | Can found a new settlement+100% production of cloths |
 | Merchantman | 4 | 4 | 60 Tools 200 HammersDrydock | Cargo space: 4 Can only defend Chance to escape to Drydock or Shipyard after losing a battle |
 | Native | 0 | 1 | 50 Hammers | Replaces free colonist Can found a new settlement +25% marsh attack +75% jungle attack +75% forest attack +50% light forest attack +1 production of fur +2 production of ore |
 | Petty Criminal | 0 | 1 | – | Can found a new settlement -2 production of Liberty Bells, Crosses, Education -1 production of Cloth, Coats, Rum, Cigars, Tools, Guns, Hammers |
 | Privateer | 5 | 4 | 60 Tools 100 Muskets 200 HammersDrydock | Cargo space: 2 Hidden nationality Can attack without declaring war Captures the cargo of defeated transports Starts with Navigation I |
 | Regular | 0 | 1 | – | Can found a new settlement Doesn’t receive defensive bonuses +50% settlement attack Starts with Veteran I, Veteran II |
 | Seasoned Scout | 0 | 1 | – | Better results from ancient ruins Can found a new settlement |
 | Ship of the Line | 8 | 4 | 300 Tools 300 Muskets 400 HammersShipyard | +50% vs.Frigate Can bombard settlement defense (-12%/turn) Replaced by Man-o-War |
 | Treasure | 0 | 1 | – | Can be transported by Galleon Can be exchanged for gold in Europe |
 | Veteran Soldier | 0 | 1 | – | Can found a new settlement Starts with Veteran I, Leadership |
 | Wagon Train | 0 | 2 | 40 Hammers | Cargo space: 2 (carries goods) |