You ready for the breakdown?

This is all according to stats supposedly from multiple militaries, including the PLA [People's Liberation Army]. You'll have to forgive me if I don't have sources all on hand, this has been stuff I've dug around for a long time and very few of my sources are in one place. A lot of it shouldn't be too hard to find, though.

Lets walk through a play-by-play.

The PLA can't just strike Taiwan out of the blue. Troops need to be moved, ships, vehicles, etc. all need to be massed. I suppose the PLA could launch missiles or perform air strikes, but that would be suicidal to do without the full invasion at the ready; Taiwan is equipped with some of the greatest military equipment in the world [thanks to the US], including some of the best air defense systems in the world. Tons of PATRIOT missile launchers and missiles, and so on. Extensive range, potentially even to the mainland.

Taiwan also has long range ordinance that likely could strike the mainland. As another commenter here mentioned, they're almost certainly in striking distance of major targets on the Chinese mainland, including potentially the Three Gorges Dam.

In this sense, Taiwan being smaller is a significant advantage; less ground to protect.

So, we get our major troop and fleet movements, alerting Tiawan and any allies to what is likely about to come. Preparations are made; freighter ships can be sunk to block off major ports, mines are laced around the island by their submarine fleet, and, of course, ground and air forces are on standby.

As soon as the PLA goes seaborne, they have to contend with long range ordinance and air strikes from Taiwan. The PLAAF outnumbers the Taiwanese Air Force significantly, but numbers aren't everything, and the name of the game for Taiwan would more likely be harassment than direct confrontation.

So, the whole way through, Chinese ships are being harassed, bombarded, torpedo'd by Taiwan's submarines, and running into minefields. They will have no harbor to dock in at Taiwan, leaving only the beachheads, of which there are only about 13 viable ones. Again, small size is a major asset for Taiwan.

All of these beachheads have been fortified to all shit. There are bunker networks under them, razor wire is readily available, mines, etc. Oil pipes also are strategically run under the beaches; they can be ruptured in the event of an invasion to turn the beach into a never ending inferno. Chemical plants have been strategically positioned near the beach heads as well; in a life-or-death situation like this, workers can be evacuated and those chemicals can be released onto the beach. We're talking super toxic shit. It'd fuck them up tremendously.

As an aside; consider the Allied invasion of Normandy. It was a bloodbath. If the Germans had exact knowledge of the chosen beaches, they would have completely slaughtered allied troops; the invasion wouldn't have stood a chance.

Now consider that not only would Taiwan know what beaches, they also would have the advantage of decades of fortifications. Do the numbers on that.

If by some incredible feat, the PLA makes it past the beaches, every highway, bridge, etc. has been acknowledged and planned so that transportation of motorized vehicles can be halted every damn step of the way. Bridges can be strategically blown out, leaving troops no easy way across, valleys and gulches laced with traps, the works. Scorched earth is totally viable as well.

Now, getting back to Taiwan's size. The PLA boasts of about two million strong IIRC; Taiwan is really not that far behind, being able to get 1 million. Given the small size of the island, the PLA's number advantage would be almost completely nullified; where can you fit so many soldiers effectively on the front?

Then there's the mountains. Taiwan is longer "north to south" so to speak; the east side is completely mountains. Taiwanese forces and civilians can retreat to the mountains, and the mountains can become another fortress in and of themselves; they can almost certainly extensively bombard the rest of the island, always getting a bead on advancing PLA forces.

Cities would turn into playgrounds for the Taiwanese forces. Steel cables can be strung between buildings to kill any helicopters or planes that attempt to fly low in urban areas. Every tall structure would be a sniper's playground.

Every square foot of Taiwan would be a meat grinder and a half for PLA forces. Could they muster more than their two million? Almost certainly. Would they have the morale to continue? No fucking way. The propaganda is that the PLA would easily crush Taiwanese forces and "reuinify" the country. The reality is that you'd probably see hundreds of thousands of bodybags before they even take the beaches. The Taiwanese would know there is no surrender, they would fight to the absolute bitter end. They would employ whatever tactics work; and given their training and equipment, they'd put up guerilla warfare that would make Vietnam look like a daycare.

The PLA knows this. If they attempt an invasion of Taiwan it will be as a desperate last attempt to hold onto their empire; the invasion would be suicide.

Any questions?