Those who try to take the control of a government, promise people to work for them according to a specific plan. But this is before taking the control of the country. When they get what they wonted, they usually forget their promise or breach it or cannot succeed in accomplishing their plans. This is can have either of these reasons:
The goals were not realistic, the government’s plans were not complete, or the government was inefficient.
In Imam Mahdi (p.b.u.h.)’s reign, the goals are realistic, for which people have waited for centuries; the plans are according to Koran and Hadiths which are guaranteed ; and his government is the most efficient of all Therefore, his achievements are drastic and can respond to all material and spiritual needs of men. Here are some of his achievements, according to Hadiths, in detail:

1. Global Justice
In many Hadiths, his most important achievement is justice, about which we previously discussed. In fact, in his time, justice is outstanding so that all parts of society enjoy such justice. All major and minor sections of society will be established based on justice and people treat each other justly.
Imam Sadeq (p.b.u.h.) says:
“I swear to God, he [= Imam Mahdi (p.b.u.h.)] will bring justice even to your houses as the coldness and heat enter your houses.”
This Hadith indicates that with the houses, which are the smallest social unit, full of justice, we can expect a global justice which fills the world. This will be done not through obligation or law, but with a Koranic order, inviting people to justice and good deeds:
“Justice does God enjoin and doing good…”
Therefore, all people treat each other justly and respect each other’s rights, even those one’s rights who are lower in rank or class.
In that society just a few self-centered people transgress the rules and Imam Mahdi (p.b.u.h.) will stop them. They will be eliminated from the society and especially, they have no chance to join his government.
This kind of global justice is the main achievement of Imam Mahdi (p.b.u.h.)’s rule. He will fulfill this aim and will clear the world from all kinds of cruelty and injustice even in minor parts of society.

2. Growth in Morality, Thoughts and Beliefs.
The justice can be universally respected when the children are brought up according to Koran and Hadiths. Besides, in Koran and Hadiths it is mentioned that growth in morality, thoughts and beliefs is on high levels in Imam Mahdi (p.b.u.h.)’s time.
Imam Baqer (p.b.u.h.) says:
“When our upholder rises up, he puts his hand on people’s heads and makes their sense and intellect perfect.”
A perfect common sense is the cause of all goodness are can do, for it is the inside messenger of everyone which calls people toward goodness, salvation and God’s orders. When they asked Imam Sadeq (p.b.u.h.) about sense and intellect, he responded:
“Sense is the one which makes you worship Allah and guides you to salvation.”
It is clear that in our world passions rule over the sense and without Imam’s rule, many people and fractions follow temptations and forget God’s orders and many rights are violated. But in Imam Mahdi (p.b.u.h.)’s time, who is the wisest man in the world, all people work due to their reason.

3. Unity and Intimacy.
According to Hadiths, Imam Mahdi (p.b.u.h.)’s followers are united and intimate. There is no hatred or hostility among them. Imam Ali (p.b.u.h.) says:
“When our Upholder rises up, the hatred leaves people’s hearts.”
Since the justice will fill the world, no one’s rights will be violated and no one will hate the others, but with wisdom and common sense all people will love each other. When people do not hate each other, their separated hearts will gather together again and they will be brothers again.
Imam Sadeq (p.b.u.h.) says:
“When the hearts are separated, God unites them and makes them love each other.”
Here if God is involved, not surprisingly He can unite the hearts and make them love others: how ever, it is difficult to understand and accept now.
Imam Sadeq (p.b.u.h.) says:
“When our upholder rises up, the true friendship and intimacy will be expressed. If someone needs money, he takes as much as he needs from his friend’s pocket and like a brother, he never stops him.”

4. Physical and Mental Health.
A serious problem of this world is deadly diseases which are incurable and mostly, they are because of pollutions, chemical, biological and atomic weapons and other misuses of environment.
Besides, illicit affairs and destroying forests and seas have caused many diseases as AIDS, paralysis, etc. Moreover, many mental diseases have caused a lot of difficulties for many people and have made the life bitter and difficult. All these are because of the wrong relation between people and the universe.
In Imam Mahdi (p.b.u.h.)’s time, all diseases will be disappeared and in the time of beauties all mental and physical diseases will be cured. Every one is healthy and strong, as Imam Sadeq (p.b.u.h.) says:
“When our Upholder rises up, God will cure all diseases of believers and will make them healthy again.”
The medical sciences will be highly developed, so that the cure for all diseases will be found. Some of ill ones will be also cured miraculously by his holy hand.
Imam Baqer (p.b.u.h.) says:
“Those who see our Upholder, if sick will be cured; if weak will be strong again.”

5. Prosperity
One special thing during Imam Mahdi (p.b.u.h.)’s time is the global prosperity which leads to affluence. It rains a lot and the plants grow more and God grants his blessings to the entire world. Imam Sadeq (p.b.u.h.) says:
“Because of Imam Mahdi (p.b.u.h.) God sends his prosperity and blessings to his servants. It rains a lot and the plants grow more [in his time]…”
There will remain no desert and all earth will be revived. Since all people follow divine values and God’s orders, He will grant them all possible prosperity. He says:
“Now if the people of those towns had but believed and kept from evil, we would have showered them with the boons of the heaven and the earth.”

6. Eradication of Poverty.
When all mines and sources appear to Imam Mahdi (p.b.u.h.) and the earth is full of prosperity and he treats all people fairly, there will be no poor in the world. Then, all economic affairs will be based on equality and brother hood; no one will deceive the others and all people will be like members of one family who are intimate and united. They won’t treat each other unjustly.
Imam Baqer (p.b.u.h.) says:
“He will give people what they need twice in a year and will pay them twice a month. He treats every one equally and continues this [until the time when there will remain no poor] and then no one will need charity [= Zakat]…”
According to Hadiths people will feel rich because they will have high souls. They are satisfied with whatever God grants them and do not wish more. They are not greedy or jealous. The holy prophet (p.b.u.h.) says:
“God makes them [= people in Imam Mahdi (p.b.u.h.)’s time] feel satisfied.”
However, people are so much ambitious and greedy before the time of his Deliverance. They do not help each other, nor do they do charity. In other words, people will feel satisfied by their hearts and the prosperity makes the life as prosperous as imaginable. The wealth will be shared fairly and contentment will become typical characteristic of all people.
The holy prophet (p.b.u.h.) says:
“God makes my people feel satisfied and Imam Mahdi (p.b.u.h.) will fill the world with justice. Then he announces: “Who needs money?” But no one stands up except one. So Imam Mahdi (p.b.u.h.) says to him: “Go to the treasurer and tell him: “Mahdi (p.b.u.h.) orders you to give me some money!” then the treasurer tells him to spread his clothes and fills it with money. When he picks it up but regrets it and thinks: “Why but they tell him: “we do not take back what we granted!”

7. The Rule of Islam and Destruction of Paganism
God has promised three times in Koran that He will make Islam universal:
“He it is who has sent His Messenger with Guidance and the true religion to overcome the other ways of life no matter how it may disgust a pagan!”
And surely God never fails his promise:
“…God shall never his promise fail.”
Certainly, the holy prophet and Imams (p.b.u.h.) have made lots of effort to fulfill God’s orders; but this event is a unique one which has never been happened before.
All Muslims wait for that day and wish God’s promise to be fulfilled. Imam Mahdi (p.b.u.h.) will come back and with the call of “I testify there is no God but Allah” and “I testify Mohammad is God’s Messenger” will make Islam universally known. They asked Imam Baqer (p.b.u.h.) about the interpretation of verse 39 of surah 8:
“Fight against them then till there be no room for persecution, and religion be for Allah unreservedly…”
He said:
“The event which interprets this verse has not happened yet. When our Upholder rises up, people will see the interpretation of this verse. So Islam will reach all parts of the world and there will remain no paganism or atheism in the world; as God has promised.”
This universality of Islam is because of its truth which will be completely revealed when Imam Mahdi (p.b.u.h.) comes back. This truth attracts every one to Islam, except those who rebel and fight against him. Surely, they will face their inevitable destiny, which is to die with his sword of justice and truth.
This unity and faith prepares the world for a united global society. All the people accept a divine law and change their relations and renew them based on the unique rules of Islam. We wait for a united world, pure environment, friendly society, faithful people which all will be fulfilled when Imam Mahdi (p.b.u.h.) comes back.

8. Public Security
Security, which is the greatest gift and the biggest wish of all people, will be attained in Imam Mahdi (p.b.u.h.)’s time. When people follow one way and respect moralities and justice can be found in all parts of society, there will be no fear or insecurity. Social security will be surely attained in a society in which people get their rights and the tiniest kind of injustice get the punishment it deserves.
Imam Ali (p.b.u.h.) says:
“…the hard time will be finished by our effort [= Imams]… and when our Upholder rises up there shall remain no hatred in the hearts; even animals live in peace, and the society will be so secure that a woman with all her jewels can travel from Iraq to Syria and no one bothers her.”
For sure, to imagine such a time is incredibly unimaginable in our time, when injustice, greed and hatred is common all over the world. But when we consider the complete elimination of evil, we can think of a secure society and on the other hand, we should trust in God’s promise. He says:
“Allah has promised unto those amongst you who do believe and do good deeds that He will make them masters in the land… and that he will change their fears to safety…”
Imam Sadeq (p.b.u.h.) interprets this verse:
“This verse is about our Upholder and his apostles.”

9. Development of Sciences
After his Deliverance, lots of secrets and mysteries will be revealed and sciences will be developed unimaginably. Imam Sadeq (p.b.u.h.) says:
“Sciences include twenty seven letters [= parts] and all the science which the prophets have brought yet, is just two of them. When our Upholder rises up, he will bring the other twenty five and will add those two as well and the whole twenty seven letters will be known universally.”
Obviously, the development and scientific achievements are a lot and incomparable with centuries ago. However, many Hadiths note that the distance between the sciences of his time and what we know now is so far away. This can be like a miracle or development in sciences.
Imam Sadeq explains the connections in his time:
“In his time one in the east sees his brother in the west.”
And in another Hadith he says:
“When our Upholder rises up God increases our Shiite’s ability to see and hear, so that he speaks to his Shiites from twenty four kilometers and they see him and hear his voice, while he is still in his place.”
Imam Mahdi (p.b.u.h.) is fully aware of people, what they do and what they say. Imam Sadeq (p.b.u.h.) says:
“If one speaks in his own house, he is afraid the walls report what he says.”
Actually, with the advanced systems of connection which are available now, we can understand these Hadiths much easier. But it is still unclear that all these will be because of advanced achievements or they are kind of miracles.