War has a lot to do with geographical location. Generally speaking, it is much easier to win at home, but it is very troublesome away from home. This is why invading other countries always requires much higher strength than the injured country.
As far as the quality of the army and the ability of generals are concerned, I think Qin is the strongest. The Qin army has a strict hierarchy and strict military discipline. It has experienced a hundred years' experience and baptism since Shang Yang's political reform, and it is complete in combat. Qin ranks among the best in the cold weapon era, regardless of the size of the legion or tactical accomplishment. Even if a country pursues its military to the extreme, even with foreign troops a thousand years later, it may not be able to beat Qin Jun.
When Qin competed for hegemony over the weekend, every war was a large corps of hundreds of thousands. At the same time, Rome conquered barbarians and swept across Europe and Asia, but it was only a phalanx of thousands of people, with a maximum of ten thousand people. Have you seen Gladiator? Maximos's Felix Corps, with thousands of men, is regarded as a provincial official, and members of parliament are worried that he will defect.
As for Macedonia, the size of the Corps may be larger than that of Rome, but it is still not as good as that of Qin Jun. At most, it is the struggle during the reign of Alexander.
Not to mention the crusaders. How many famous commanders were there in so many Crusades? How many victories have changed history? The relationship between the Pope and the small countries in Western Europe is pure nonsense. Have you ever seen heaven? Hundreds of cavalry dare to fight. Saladin pulled 200,000 troops from Damascus, and Jerusalem was dumbfounded. The protagonist Beilian is a natural military talent, but he can only actively resist the Arab Massacre. That guy in the southwest of Drew didn't even know to follow the current when he was fighting and marching. He didn't listen to advice and was wiped out. At the end of the film, King Richard of England continues to lead the expedition. He was a famous hero in European history at that time, but the expedition was still a mess. On the way back to China, he was detained by Italy, and his younger brother usurped the throne at home. Thanks to Robin Hood's ransom for the royal family, he came back. Of course, these have their own personal reasons, but they also reflect the universality of that era. Their wars were all at this level, and the European armies in the Middle Ages were not as colorful as ours.
Secondly, when it comes to national strength, to be fair, I don't think China's ancient economy can be much stronger than that of Europe at the same time. Although we have a vast territory and abundant resources, we are also at war all the year round. Under the background of fighting without starving people in the era of cold weapons, the level of all countries is very low, and they have been struggling on the edge of food and clothing for a long time.
The gap lies in the dispatching ability of the state and the government. China has a feudal history of more than two thousand years. The isolated environment and national culture have created the form of government that we pursue centralization. Although there are differences in strengths and weaknesses in the past dynasties, they all love and eagerly expect to achieve the goal of "one family under the world". Under this premise, the control and deployment power of the feudal dynasty was also first-class. Orders must be followed, and prohibitions must be stopped. No one dares to disobey the orders of the emperor. If you violate military orders, the emperor will hit whoever he says, unless you can't beat him.
On the other hand, in Rome, the Senate has the final decision on the system and state, as well as administrative and military affairs. Even if warlords can be independent, there are only a few thousand people in their hands, such as Caesar's Gaul army. Moreover, there are two consuls in Rome, which are designed to contain each other, with the Senate in charge behind them. A large group of slave owners and nobles were very powerful, and the administrative procrastination had reached a considerable level, which largely caused the degeneration and corruption of the country later. Rome was later transformed into an imperial system, and the emperor was not an absolute monarch, nor was he necessarily hereditary. He often abdicated and the guards usurped the throne. He was even ruled by four emperors, and his strength gradually weakened. After the split, the corner of East Rome was safe for thousands of years, and then it was destroyed at the moment when the Turkish cavalry arrived.
Macedonia is a small country. Except for Alexander and his father, who have been brilliant for decades, the rest of the time is hard, not to mention the reserve forces. Alexander fought all the way to replenish supplies, just like Japan invaded China.
The Crusade was not a national organization at all, but a joint crusade convened by the Pope in the era when Christianity was powerful. It can be said that it is a United army, and it has not been United for a long time, that is, during the chaotic period of their respective actions, they also fought internally because of religion and interests. Warlords, lords and rich families often have difficulties in military operations because money and land are tied to each other and military expenses are not given. What about the war reserve?
Finally, your question, first of all, when the west invaded our country, it was not dominant. It was a long-distance raid, far from home, lacking supplies, tired from marching, unfamiliar in a strange place, and not afraid of freezing to death when crossing the Pamirs, so we easily hit him halfway. Gansu, Guanzhong and northern Shaanxi are all tough guys. The cavalry will give him a head-on blow, and Wan Li's attack will be over.