Units

§ In Civilization IV, the term "unit" refers to anything that can move around the map. There are a number of different types of units in play - military units, work units, missionaries and great people - with military units forming the bulk of them.
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Unit Statistics

§ All units have two basic statistics (or "stats"): movement speed and combat strength.
§ Movement Speed
§ A unit's movement speed determines how quickly the unit can move around the map. Movement speeds generally range from 1 to 8. Some units have movement speeds of 0, which indicates that these units have special rules governing their movement. See the section on Movement for details.
§ Combat Strength
§ A unit's combat strength determines how tough the unit is when fighting an enemy unit. Combat strengths range from 1 to 40, and this base strength can be affected by many modifiers (see Combat). Some units have combat strengths of 0, which indicates that the unit cannot fight or has special rules governing combat. See the section on Combat for more details.
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Acquiring Units

§ You can obtain units in a number of ways:
§ Game Start
§ You have two or more units at the start of a game. At least one of these units is a settler; the remainder are workers or military units.
§ Tribal Villages
§ You may gain a new unit when one of your units enters a tribal village. (Or you may gain gold, technology, or experience - or the village may be hostile and generate barbarians to attack your unit.)
§  Capturing Units
§ Workers and Settlers are automatically captured when attacked by a military unit, or when they are in a city that is captured. (Note that settler units turn into workers when captured.)
§ Constructing Units in Cities
§ You construct most of your units in Cities. See below.
§ Generating Units in Cities
§ Your cities generate Great People units automatically. See that section for more details.
§ Gifts from other Civilizations
§ Very rarely, a civilization may give you a unit.
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Constructing Units in Cities

§ As discussed above, most of your units come from your cities. Cities also construct buildings (plus other specialized items). They can only construct one item at a time - balancing the need for units against the need for buildings is crucial to your success in the game. Following is some information about constructing units; more can be found in the Cities entry.
§ Choosing Units to Construct
§ When a city is ready to begin constructing a new unit or building, the city construction menu appears. This lists everything that you can construct in that city, as well as the time required for construction. Click on the unit/building you wish to build and the city will begin construction immediately. If you wish to change what a city is constructing, go to the city screen and click on the new item you wish to build.
§ Unit Availability
§ Not all units are available for construction at the start of the game. Many units have Technological requirements, and some units require that you have access to one or more Resources; for example, you cannot build a Swordsman until you have researched Iron Working and have access to Iron. Also, a few units have Building and/or Religious prerequisites.
§ Construction Time
§ A unit's construction time is based upon the city's Production. The greater the amount of production a city has, the faster it can train new units.
§ Unit Support Costs
§ The number of free units you will be able to have is affected by the Difficulty Level you are playing. Once you have surpassed the number of free units you are awarded, you will be charged per unit over your free unit total. Each unit costs one gold per turn to maintain. Certain Civics modify the number number of free units that are available to you.
§ Unit Away Costs
§ Units that are not within your civilizations borders cost additional money to maintain and supply. Invading an enemy civilization will cause a serious strain on your budget.
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Selecting Units

§ A circle around a unit's indicates that the unit is "selected" and waiting for your orders. The computer auto-selects each unit waiting for orders in turn; if the unit already has orders the computer will not select that unit. You can also click on any of your units to select them manually.
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Unit Orders

§ When a unit is selected, you can order it to move (see Movement), or to attack (see Combat). The unit might have other options available to it: these are displayed in the unit's "order box" at the middle-bottom of the screen. To give a unit an order, click on the appropriate icon in the order box (many orders have keyboard shortcuts, as well).
§ There are a wide variety of orders available in Civilization IV. The specific orders available vary from unit to unit and may also vary depending upon the unit's location, health status, experience, and so forth.
§ Other Orders: Bombers may have bombing orders; Fighters may have recon orders; Galleons may have transport orders; and so forth. Check on a Unit's Civilopedia entry to find out what a unit can do.
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Selecting Multiple Units

§ You can select two or more units and give them both orders simultaneously. All of the units must be in the same space on the map. To do so, click on one unit, then shift-click on the other(s). All units will be selected.
§ Moving Multiple Units
§ If two or more units are selected and you give them orders to move, they will do so in a group, at the speed of the SLOWEST unit. (Note: it is often smart to move a settler and a military unit simultaneously to make sure that the settler doesn't get destroyed by the first animal or barbarian it runs into.)
§ Multiple Unit Combat
§ If you have the stack attack option enabled and you order two or more military units to attack an enemy unit, the most powerful unit against the defender will attack that unit. If that unit's attack is unsuccessful, the attack won't continue automatically; if you want to attack with another unit, you'll have to give that unit new orders. However, if you hold down the ALT key when ordering an attack with multiple units selected, the units will perform a stack attack with combat resolving immediately.
§ Multiple Unit Improvements
§ If you have two or more workers selected, you can order them both to work on improvements. The workers' combined efforts will speed up construction considerably.
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Promotions

§ A combat unit gets "experience points" for winning battles. Enough experience points will earn that unit promotions.
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Unit Types

§ Each unit belongs to a different "group"; for example, Muskets are Gunpowder units and Knights are considered Mounted units. Many of the promotions and natural unit abilities are based upon these unit types. For example, Spearmen naturally get a huge boost when fighting Mounted units, and the Shock promotion grants a unit +25% against Melee units. Consult the entries on Promotions and on each individual unit for more information.
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