StarCraft: Brood War/Terran Mission 5B: Emperor's Fall (Birds of War)

The "Emperor's Fall" mission occurs in two ways, depending on how the previous mission was completed:
 * Birds of War
 * You must defend against Battlecruisers and their Yamato guns
 * This mission occurs if you destroyed the nuclear silos
 * Ground Zero
 * You must defend against Ghosts and their Nukes
 * This mission occurs if you destroyed the physics labs

Getting Started
You begin this mission with a modest base containing only one Marine and four SCVs. At first it appears you also have a fairly wide, if sparse, network of Missile Turrets as well. However, these will soon be destroyed by eight Battlecruisers. In response, you receive reinforcements in the form of eight Goliaths, four Marines, and four Ghosts, being transported through three dropships. If you haven't already, start gathering minerals with your starting SCVs, and build as many more SCVs as you can to get the ball rolling. Also, remember those enemy Battlecruisers? Yeah, they're coming for you. Your Ghosts come pre-loaded with the Lockdown ability, so as soon as the Battlecruisers come in visual range, use Lockdown and destroy them as fast as possible with your Marines and Goliaths. You will most likely lose some (if not most) of your reinforcements during this attack, but try to preserve your Ghosts as you won't be able to replace them for a bit.

As soon as you make it through this initial assault, begin preparing for the many, many Battlecruisers that will be sent your way. Build one or two Bunkers at each of the three land entrances to your main base, and then construct a thick network of Missile Turrets in the north half of the starting area and round out your base defense with a few Goliaths. You will also constantly have to rebuild these Missile Turrets as the enemy has access to Yamato Guns and is not afraid to use them. When you have a chance, build a few Siege Tanks to guard against land assault and four to six Wraiths to chase down Battlecruisers that decide to run.

As you further develop your base, note the four major types of attacks as per the Ground Zero version of this mission (note that the enemy in this version will generally throw Battlecruisers at you instead of Wraiths, but be prepared for both nonetheless).

Venturing Out
Get a feel for the surrounding terrain with a couple Wraiths. Scouting with ground units isn't recommended until you have a Science Vessel free to send with them, as there are a number of Spider Mines scattered around the map that with quickly destroy even your toughest units. The first expansion you should make is directly north of your start position, and is completely undefended and loaded with resources. Just make sure to defend the position properly: network of Missile Turrets, a few Siege Tanks, and either Goliaths or Wraiths (Wraiths are recommended as this particular valley can get somewhat cramped).

Next, take a Science Vessel, a group of Goliaths, a group of Siege Tanks, and a couple Medics northeast. Move carefully and clear out Spider Mines as you go. Eventually you will encounter a small Blue base. Move in, siege your Tanks, and wipe them out. Take up a defensive position and build a tertiary base to take advantage of your newfound resources. When you've settled here, clear out the area just across the bridge to the north of this area to cement your position.

After you've secured these areas, begins churning out Goliaths and Siege Tanks while maintaining at least one full group of Wraiths. These will be your primary offensive force. If you need more resources, there are large resource nodes at the northwest and southeast corners of the map with partial defenses.

The Attack
Push north from your eastern base with your offensive force; make sure at least two SCVs, two Medics, and a Science Vessel tag along and always be wary of Spider Mines. Use cloaked Wraiths to take out any exposed Siege Tanks (there will be a few on top of various walls that you need to take out before advancing ground troops); the enemy will Comsat as soon as the Wraiths open fire, but you should be able to take out your targets before defensive units can get in position to attack. Alternatively, Yamato Gun them with Battlecruisers if you've chosen to build any.

The biggest threat as you head north are enemy Ghosts using Lockdown on your units and enemy Siege Tanks hitting you unexpectedly. Advance slowly, take your time, and you should be fine. Also make sure to maintain your various bases as you attack as Red will take every opportunity to hit your weak spots with Battlecruisers and Wraiths.

After you clear Blue out of the way, build a couple Factories where their base used to be and pump out a few more Goliaths and Tanks. Only a relatively thin strip of Red defenses lies between you and Mengsk's Command Center. Cloak your Wraiths and take out whatever Tanks lie on their borders, then advance your ground troops as you have been. Red will put up a fight, but if you can get even a few Tanks and Wraiths up to the Command Center, victory is yours.

Alternative
This mission can be completed in a very easy way. You should create a good defence. Build 20-25 missile turrets, 6-8 bunkers and 4 siege tanks. Afterwards you should expand to the east and north mineral fields. Also make some bunkers and turrets here. When you have done this you should create about 3 nuclear silos and 1 comsat station. Research personal cloaking for your ghosts and arm your silos. Use your comsat station to scout your way to their command center, because there are spider mines on the way. All you have to do is crush your foe with your nuclear bomb-shooting ghosts (cloaked of course). Make sure you destroy all missile turrets on the way. Also make sure you reveal the way you want to walk by using your comsat station, because those spider mines are quite annoying. This strategy consumes a lot of time, but it works just fine. Good luck!