The United States turns its massive offensive military into a much smaller force, switching its priorities to domestic matters, beginning with using the U.S. military budget to fill the gap in Social Security's trust fund left there by past congresses and presidents who spent the money on other things, and continuing onward in the same theme.
As the U.S. is downsizing its military, China becomes a world superpower, building new supercarriers and becoming a dominant sea power in addition to a growing economic power. Eventually, China goes down the route of conquest. China invades all of Continental Asia, Japan, Australia, and New Zealand. They then turn their forces in the Middle East until reaching the shores of the Mediterranean Sea. This concerns the European Union which sends a joint fleet of ships to the Straits of Gibraltar, only to be pinned down there.
China instead throws its resources into attacking the Caribbean. Due to the Monroe Doctrine, new President Bill Baker, who came to office on a pro-war platform, has to make a critical decision: to try to halt them with conventional forces, or use nuclear weapons.
The U.S. must make a decision as the Chinese invasion forces in Central America gather steam: to build traditional naval super-carriers to meet the new Chinese ones, or to build highly experimental missile supercruisers capable of firing thousands of missiles at once, showering its target with overwhelming force while having a crew of only around 100 due to the extent of automation. They might be more effective but are also untested, and the U.S. does not have the resources for both. Baker decides to back the supercruisers.
As the likelihood of invasion via the Gulf of Mexico comes, many Americans leave the exposed states. The Joint Chiefs of Staff are not sure if this is another diversion attempt and the Chinese might come from the east or west coasts. The U.S. President orders the military to plan for those eventualities as well. A full war economy with full mobilization is called up, including all able-bodied women, which includes the U.S. President's daughter.
Baker refuses to order a nuclear strike and orders the military to meet the threat with conventional arms come what may. He is convinced any nuclear strike will lead to a series of escalating exchanges that will leave the two countries not worth the fight. The U.S. then braces for an invasion.
Invasion provides the following tropes:
- Alternate History: Just like Dragon Strike, it is set in the future but the point-of-divergence only states that China has built up its military in preparation for conquest. Since this was written before 9/11, it seems the attacks and the War on Terror have been butterflied away.
- Bittersweet Ending: The Chinese withdraw back from the United States after a moderate Lieutenant takes over command. America's new prototype supercarriers are placed into commission, ensuring that the U.S. Navy gets back it's blue-water navy status. However, much of the Eastern Hemisphere is under Chinese occupation and no peace treaty has yet to be signed.
- China Takes Over the World: The main plot line of the novel is a risen China hellbent on world domination. By the time they reach the continental United States, China has swallowed all of Asia, Southeast Asia, Japan, Australia, New Zealand, the Middle East, Turkey, Central America, and parts of South America.
- Connected All Along: This book deals with it a lot. See also Everyone Is Related and Long-Lost Relative below.
- President Baker and Han Zhemin (civilian administration of occupied America) were classmates in college before hence why he makes deals with him without the American public knowing about it.
- Dirty Communists: How the Americans see the invading Chinese, naturally.
- Elites Are More Glamorous: Part of the novel deals with a lone American Special Forces operator deep within enemy lines conducting hit-and-run attacks on Chinese forces.
- Enemy Civil War: U.S. intelligence networks point out that the civilian leadership in Beijing is against the PLA's offensives throughout America, knowing how costly it is. That is where the Americans exploit it the most. In the climax, Lieutenant Wu executes the Chinese general responsible for the invasion of America right as President Bakers surrenders to the said general. Lieutenant Wu then orders all Chinese forces to head back to China.
- Everyone Is Related: Not in the strict sense, but Stephanie Robert's mother had an affair with a Chinese diplomat and her aunt had a child with a Han Zhemin. Her aunt is the biological mother of Lieutenant Wu.
- Friendly Enemy: U.S. President Baker makes behind-the-scenes negotiations with Han Zhemin, the Chinese administrator of the occupied areas. It is notable that Baker and Han were classmates in college before and do not bare hatred for each other, but our considered enemies due to the war with U.S. and China.
- From Bad to Worse: The situation with the Chinese military conquest in which the U.S. refuses to come to aid countries under Chinese invasion. The novel mentions the U.S. could have stopped the Chinese in the Himalayas and in Diego Garcia but didn't choose to act. Because of their inaction, China gobbles up most of the Asian continent, Oceanian, and Central America. This comes with a large military force on America's doorstep, poised to invade. All while America continued to downside its military.
- General Ripper: The Chinese General. In-story, his most famous deed is his response to Israel's use of tactical nuclear weapons against Chinese troops - he laid siege to Tel Aviv and planted nuclear demolitions charges in the city, taking care to ensure that as many people died as possible.
- Good Guns, Bad Guns: The U.S. military's standard issue M16 assault rifle to the Chinese standard issue Type 95 QBZ.
- Idiot Ball: The previous U.S. President who refused to fight the Chinese at an early stage while downsizing the military. Doubles as Jerkass.
- Invaded States of America: The title itself already gives this away.
- I Surrender, Suckers: President Baker's plan to surrender to the Chinese forces on the bridge from Arlington, VA to Washington, D.C. which was supposed to have him killed by a Friendly Sniper. Instead, a Chinese lieutenant then turns on one of the Chinese generals on the bridge and kills the said general. This enables the lieutenant to take over and order a withdrawal of Chinese forces from the USA.
- Lady of War: Stephanie Roberts Baker, the daughter of the President of the United States, at the young age of 18 is serving the military due to the Chinese invasion. This was a complete opposite of her teen life which was composed of soccer and partying.
- La Résistance: Various American resistance fighters are spread out behind Chinese military lines.
- Long-Lost Relative: Stephanie Baker and Lieutenant Wu. Stephanie's aunt had an affair with Han Zhemin in which she is the biological mother of Wu, thus making them cousins. Wu explains this to Stephanie once she was captured by the Chinese forces. Stephanie also notes that Wu looked Caucasian more than Chinese.
- Luke, You Are My Father: Lieutenant Wu when he visited the home of his biological mother which turned out to be Stephanie Robert's aunt.
- Macross Missile Massacre: The U.S. Navy's prototype super-cruisers are capable of raining down thousands of missiles on enemy forces. Unfortunately, only a few have been built by the time the Chinese invade the continental USA. It did see a bit of action in the waters off the coast of Cuba, sinking a PLA-N landing ship tank.
- The Mole: Clarissa, the White House staffer, who is a spy for the coup plotters against President Baker.
- Next Sunday A.D.: Although the novel does not state when it is set, it is implied to be set around the late 2000s or early 2010s.
- One Degree of Separation: Lieutenant Wu to his biological mother: Stephanie Robert's aunt, who had an affair with then-diplomat turned administration of the occupied areas; Han Zhemin.
- The Quisling: Several American civilians living in the occupied areas are forced to denounce the USA and praise China.
- Sequel Hook: Earlier in the novel, it was hinted that the U.S. Navy will work on super-cruisers to counter the Chinese invasion. From repelling the invasion, the U.S. and their allies will go on the offensive and liberate the occupied countries from China before taking the war to the Chinese mainland. However, this never happened and 17 years later, Eric L. Harry has not made any mention of a sequel since.
- Sidekick: The American Special Forces operator has a Royal Marine attaché with him collecting on enemy data. Sadly, we only get to see him in one chapter as he returns to London to report his findings on Chinese military movements in the U.S.
- The Squadette: Female soldiers, some only as old as 18, including our titular hero Stephanie Baker, are serving in the U.S. military to fight against the Chinese.
- While Rome Burns: Basically the United States prior to the Baker administration. They refused to respond to calls for military intervention against the Chinese war machine because they thought it was not worth it to spend resources in fighting China. This later comes back to bite the new Baker administration in the ass.