The wars experienced by the Second and Fourth Fleets were known as the "Oort Cloud Battle" or the "Second Battle."
The meaning of "Second Battle" was that it was the second large-scale battle with the Trisolarans.
In November of the first year after deterrence, the four legions of the Solar System State, totaling more than twenty-eight thousand warships, set off together to confront the enemy at the Oort Cloud.
Right after the end of the "Second Battle," the Trisolaran Second Fleet resumed acceleration; it was originally estimated that they would reach the Kuiper Belt in two years, but now they needed only a little over eight months.
Four months had already passed, which meant that if no one intervened, they would reach the Kuiper Belt in March of the following year.
This once again left the military officers of the Solar System State puzzled: what were they up to? Why didn't they simply enter lightspeed? That way, they could appear at the Kuiper Belt defenses in just over a dozen days and trap the fleet of the Solar System State in the military stronghold.
It was not until the astronomers of the Solar System State, using the most advanced telescopes, found a faint outline at the location where the Second Fleet had dropped out of lightspeed.
The lines that appeared against the pitch-black backdrop sketched out a rough circle, like a soap bubble in the night sky.
An obvious fact surfaced: Trisolaran lightspeed spaceships left behind a trail when entering and exiting lightspeed!
When the astronomers looked again at the battlefield of the "Second Battle," sure enough they found two small, faint "soap bubbles" there.
Such trails were difficult for humanity to detect, but were believed to be blindingly obvious to some advanced civilizations, like lighthouses.
Therefore, the Trisolarans were very restrained in using lightspeed travel around the Solar System.
When the Trisolaran advance teams realized they were no match for the Second and Fourth Legions, they risked short-distance lightspeed travel.
This trail was as obvious as a cosmic broadcast, and even more terrifying! After all, it proved that the civilization of the star system had the ability to travel at lightspeed, and would be subject to priority strikes from the Dark Forest.
And the Second Fleet probably had the confidence to win, so they wouldn't take such a risk.
Jiang Yu also witnessed the grand departure of over three thousand warships from Pluto.
They would gather roughly a hundred astronomical units away, then divide into four squadrons to meet the enemy from four different directions.
Jiang Yu knew in his heart that this battle might not happen.
After all, the cosmic broadcast from Starship Earth was about to be received by the Trisolarans.
Even if Starship Earth hadn't carried out a cosmic broadcast, at Jupiter's industrial base, ten Gravitational Wave Emitter warships similar to the Gravitational Force were under construction.
Rediaz personally oversaw the construction, which would be completed in another half a year.
According to meticulous calculations by the Academy of Sciences, the current signal interference by the Trisolarans around the Solar System had roughly formed an ellipsoidal sphere with a diameter of five thousand astronomical units.
By then, each of the ten warships would be equipped with an escort ship and set off in ten different directions, forming a new deterrent once they traveled beyond five thousand astronomical units.
It could be said that the defeat of the Trisolaran advance teams had already given Jiang Yu an absolute advantage.
However, Jiang Yu did not stop the expedition, and despite knowing that the battle would bring great losses, these two million soldiers bravely embarked on their journey.
The moment they departed, they proved they were warriors of the Solar System State!
As long as the gathering was completed, the purpose of training the troops would be achieved.
With the victory of the "Second Battle," sure enough, the battlefield on Earth underwent enormous changes.
Firstly, The Waterdrop didn't participate in combat anymore, and each time the PDC went to battle, they became more and more cautious.
Only the ten million pseudo-army recruited by Sophon were still fighting fiercely, and although they suffered heavy losses, Sophon's second and third recruitments still received the response of several hundred million people.
The PDC began to make some moves, first by sending people to contact the Solar System State under the guise of being captured by the Solar System United Military.
However, Jiang Yu had no intention of giving them the chance to hedge their bets; he required them to declare war on the Trisolarans and completely end their subordination before continuing negotiations.
For now, the PDC did not have the courage to do so.
But when responding to Sophon's orders, they were no longer so eager.
As the immigration plan kept getting delayed, Sophon once again used "The Waterdrop" to destroy a major human city.
Zhuang Yue did not pay any heed, only making a symbolic blockade when "The Waterdrop" left.
Jiang Yu gave her new orders: to occupy all territories on Earth except for Australia and New Zealand and to expel all PDC citizens.
The armed forces under Zhuang Yue's command were rapidly expanding and once again finding themselves stretched thin, powerless to do anything but watch "The Waterdrop" flee from the Earth like a fugitive.
It was only after Jiang Yu ordered the industrial department to allocate certain productive forces to Earth that Zhuang Yue's situation improved slightly.
Meanwhile, the PDC became even more miserable, driven not only by Sophon's coercion but also by the expulsion by the First Legion.
Jiang Yu's orders were clear: to stay in their homeland, they had to renounce their PDC citizenship, and the Solar System State was not going to offer them citizenship in the meantime either.
As a result, hardly any citizens were willing to stay and accept the rule of the Solar System State.
The victory of the "Second Battle" also spurred the PDC citizens' spirit of resistance.
After the "Second Battle," the number of those in the Resistance Army soared, surpassing ten million.
Zhuang Yue provided them with a great deal of assistance, tying up a large part of the puppet army's forces.
However, their battles were extremely brutal, especially in areas under PDC control, where the puppet army had intelligence from Sophon and an absolute advantage in equipment, leading to heavy sacrifices among the Resistance Army.
Eventually, at the end of December, a year after the ultimatum, the PDC completed the immigration as Sophon had demanded.
The crowded population and scarce resources had long turned Australia and New Zealand into a living hell, with widespread incidents of people starving to death.
But they could not possibly imagine that this was just the beginning of their misfortune!
After completing the immigration, Sophon ordered the puppet army to destroy all ports and power stations.
Then Sophon convened the United Nations assembly.
"The immigration is over," Sophon bowed to everyone and said, "This is a great feat, yet it pales in comparison to the original humans who emerged from Africa tens of thousands of years ago.
"A new era for two civilizations has begun."
PDC national representatives, as well as the high-ranking officials of Fleet International, all looked ashen-faced.
Sophon continued, "In order to annihilate the Solar System State, the magnificent Trisolaran Interstellar Fleet instantly began to accelerate after the 'Second Battle' ended five months ago.
"It is estimated that in two months' time, they will defeat all armed forces of the Solar System State, and in three months, break through the defenses of the Kuiper Belt.
"Then they will rapidly obliterate all industrial forces of the Solar System State, ensuring their Gravitational Wave Signal Spaceships will never be able to embark.
"You should be aware that the Second Fleet has more than four hundred warships, with combat power six to eight times that of the vanguard. And the Solar System State, having suffered heavy losses in previous wars, is far from a match for the Second Fleet!
"Therefore, before the magnificent Trisolaran Fleet brings you all a wonderful new life, everyone must endure a difficult three months.
"Now I declare: Australia and New Zealand are completely isolated from the outside world. Anyone attempting to leave Australia will be treated as an invader of the Trisolaran World and firmly eradicated!
"During these three months, the use of any modern technology, including electricity, is prohibited."
"This is slaughter!" someone screamed hoarsely in the assembly.
The current food supply of the PDC was only enough to sustain eight billion three hundred million people for one month.