Career Military Campaign
     A long-term and incredibly satisfying campaign, the Career Military campaign starts your characters out as amateur soldiers in the regular military service.  You follow your character through his career, through training operations, boot camp, and maybe even a war or two.  As your character grows in level, you make decisions for where his career goes, and how he develops.  While it takes awhile, this campaign eventually ends up with very personal and memorable characters and plot-lines.
     Advantage- Character Development: this campaign is all about character development.  While your character might start as a recent high-school grad enlistee, he eventually becomes an experienced soldier.  You grow with your character, and live through him.  The characters you develop and their adventurers are bound to be some of the most memorable you'll ever have.
     Disadvantage- Slow: while certainly memorable, this campaign does take time to develop.  Characters don't jump right into the action.  They go through boot camp and numerous training operations before going out into the field.  This can bother some players, who don't like the idea of playing amateurs, and would rather jump right into a character.  This campaign is for those who love to role-play.
     Recommended Classes: Soldiers, maybe Protectors in a Career Cop Campaign
     Recommended Levels: 1st
     Recommended Equipment: none permanently, given out during training and when put out on assignment.

Cop Campaign
     Perfect for fans of the Cops television show, this campaign puts the characters in the role of common cops, preferably in a big city.  They may be parts of special narcotics or vice units, or even a SWAT team.  Confronted with the every-day obstacles and adventures of the common police officer.
     Advantage- Variety: anyone who's seen Cops or any similar show knows about the variety of situations cops and police officers are thrown into in their lives.  This same type of variety makes this an interesting campaign.  One day they may be taking down a violent gang, the next negotiating with a drunken clown.  As opposed to many CoD campaigns, which tend to be serious, this campaign, while still serious, also has room for comic relief.  Because of the variety, this is one campaign that rarely grows old.
     Disadvantage- Small Time: for players used to saving princesses from giant dragons, the common jobs and achievements of police officers might seem rather mundane.  While spy and military campaigns allow you to influence international events, cops rarely do things that influence any farther out than their home town.  Yet, it can still be fulfilling, sometimes even more so, since the people who are pretending to help resemble the real people around you.
     Recommended Classes: Investigators, Protectors, maybe some ex-Soldiers or Civilians
     Recommended Levels: 2nd+
     Recommended Equipment: a sidearm and vest for each character, a shotgun in the car.  Every character has a few pieces of equipment like a breathalyzer and flashlight.  Special units may have surveillance units or heavier weaponry.

Espionage Campaign
     The traditional campaign for Call of Duty, this campaign focuses on the realistic (or at least Clancy-esque) operations of real-world spy agencies.  Your characters take on enemy agencies, terrorists, and maddened dictators in a quest for information and control.
     Advantage- Flexibility: the spy campaign is incredibly flexible, and allows you to play a variety of characters, in a variety of environments.  Spies aren't usually career spooks.  They often come from other agencies, such as military units or police agencies.  And adventures in a spy campaign can take place anywhere, from the buildings of Paris to the jungles of Indonesia.
     Disadvantage- Subtle: the realistic spy campaign takes brains, and it takes patience.  Running around shooting things isn't the way to acquire sensitive information.  Much of the "action" is going to be of the non-violent type: bugging houses, sneaking around, organizing stings.  It can still be exciting, if done right, but is definitely for a more subtle audience.
     Recommended Classes: any
     Recommended Levels: 3rd+
     Recommended Equipment: a sidearm each character, and some specialized equipment such as surveillance equipment and discrete video/audio recorders.  Light armor only, and only light weapons that won't be noticed too easily.  Some characters, such as sharpshooters, may have special, more powerful weapons, and characters may have access to heavier weaponry and armor for particularly violent encounters.

FBI Campaign
     The premiere federal law enforcement agency for the United States, the FBI handles violent crimes, bank robberies, kidnappings, domestic counter-terrorism, and counter-intelligence.  They are expert investigators, delving through mysteries with practices skill.
     Advantage- Intellectual: this is definitely the thinking man's campaign.  Character's don't frequently go out and shoot at the bad guys.  Instead, they arrive at crime scenes and use their skills to investigate.  The players get to uncover clues that you give them and solve the mysteries themselves.  It can be incredibly satisfying, especially because the players are actually doing it themselves.
     Disadvantage- Intellectual: then again, not everyone likes the thinking game.  Many like action-packed, shoot-em up games, and this isn't one of them.  Gunfights are something to avoid here, not seek out.  Also, some players might not have the patience enough to sit back, collect the clues, and solve the mystery.  It takes good role-players to play this campaign, and the GM should be careful not to bore his players if he chooses to run it.
     Recommended Classes: Investigators, maybe some ex-Soldiers, ex-Protectors, ex-Academics, or ex-Civilians
     Recommended Levels: 3rd+
     Recommended Equipment: a sidearm for each character, a variety of special equipment available on request.

Special Operations Campaign
     The ultimate shoot'em-up campaign, the Special Ops campaign is a pure adventure.  The dungeon hack of Call of Duty, it puts players in the role of people who make war for a living.  They are experts.  Whether Army Special Forces, Army Rangers, British SAS, Russian Spetznaz or another type of unit, each character fills a slot in his military unit and, together, they take out the enemy.
     Advantage- Action Packed: with guns blazing and satchel charges exploding, this game gives you more minute-for-minute action than any other.  You barely even need a plot, just some soldiers and terrain.  This isn't to say that it's just point and shoot; making strategy decisions takes a fair amount of thinking, and can create much variety in the campaign.
     Disadvantage- Plot Thin: while it's satisfying in the short term, this campaign is weak and can get tedious in the long-term.  Without much of a plot line, this campaign can run its course quickly.  Plot lines can easily be worked into the campaign, but they are often drowned out by the action.  Such campaigns can be fun for parties or short runs, but aren't necessarily terrific for long-term games.
     Recommended Classes: Soldiers, maybe some multi-classed Operatives
     Recommended Levels: 5th+
     Recommended Equipment: heavy guns, heavy armor, heavy explosives, heavy everything.