Before he passed away, Sayyiduna Abu Bakr (radi Allahu anhu) consulted the senior Sahaba and elected Sayyiduna Umar (radi Allahu anhu) as the second Caliph of the Muslims.
He was the son of Khattab and is famous in Islamic history as "Al Farooq" or "One who Distinguishes between Right and Wrong." His acceptance of Islam is also very famous.
AS A CALIPH
Sayyiduna Umar (radi Allahu anhu) was a very brave and straight-forward person. He was tough and uncompromising in Islamic principles. He was a great and talented ruler. During his Khilaafat, vast areas of the Roman and Persian empires and the whole of Egypt were brought under Islamic rule. He was also a gifted orator. He was very concerned for the welfare of the Muslims. He left a honourable legacy for Muslims after him. The Holy Quran was given to him by Sayyiduna Abu Bakr (radi Allahu anhu) for safe-keeping.
APPOINTS NEW COMMANDER
Sayyiduna Umar (radi Allahu anu) was a strong disciplinarian. He noticed the tremendous popularity of Sayyiduna Khalid bin Walid (radi Allahu anhu). He felt that people will lose trust in Almighty Allah and put all their trust in Sayyiduna Khalid bin Walid (radi Allahu anhu). He feared that the people may think too highly of him, thereby possibly increasing the self-esteem of Sayyiduna Khalid bin Walid (radi Allahu anhu) which would also breed arrogance, so he removed Sayyiduna Khalid (radi Allahu anhu) and appointed Sayyiduna Abu Ubaidah bin Jarrah (radi Allahu anhu) as the Commander in Chief of the Muslim army.
Sayyiduna Khalid bin Walid (radi Allahu anhu) happily accepted the orders of Sayyiduna Umar (radi Allahu anhu) and then served as an ordinary soldier. This is an example of the Islamic teachings of obedience to leadership!
DEFEAT OF THE PERSIANS
Sayyiduna Khalid bin Walid (radi Allahu anhu) had left Sayyiduna Muthanna (radi Allahu anhu) in command of the Muslim forces on the Iraqi front when he rushed to Yarmuk. Sayyiduna Muthanna (radi Allahu anhu) was finding it difficult to counter the enemy and went personally to Madinatul Munawwarah to ask Sayyiduna Abu Bakr (radi Allahu anhu) for re-inforcements. Sayyiduna Abu Bakr (radi Allahu anhu) had by that time passed away.
Sayyiduna Muthanna (radi Allahu anhu's) absence from the Iraqi front made things worse there. The Iranians regrouped under the command of Rustam and recaptured the lands taken by the Muslims. Rustam sent 2 columns of his army, one to Hirah and the other to Kaskar.
Sayyiduna Umar (radi Allahu anhu) sent Sayyiduna Abu Ubaidah (radi Allahu anhu), as Commander, to deal with the situation. Both the Persian columns were defeated. Rustam sent an even larger army and defeated the Muslims.
Sayyiduna Umar (radi Allahu anhu) raised another army and defeated the Persians. But the Persian court sent yet another larger army, and forced Sayyiduna Muthanna (radi Allahu anhu) to withdraw. The report of the new situation was sent to Sayyiduna Umar (radi Allahu anhu) and reinforcements under the command of Sayyiduna Saad bin Abi Waqqas (radi Allahu anhu) were sent.
The Persian and Muslim army met at Qadisiyah. After a long battle on several fronts, the outnumbered Muslim army defeated the 120 000 Persian soldiers and recaptured Hirah and their areas in the year 14 A.H. (636 C.E).
DEFEAT OF THE ROMANS
Muslims laid siege to Damascus during Sayyiduna Abu Bakr (radi Allahu anhu's) rule as Caliph. It continued, after he passed away, and lasted 70 days during the rule of Sayyiduna Umar (radi Allahu anhu). After the long siege, Sayyiduna Khalid bin Walid (radi Allahu anhu) took the Romans by surprise and entered the city. The Governor surrendered and a peace treaty was signed.
CONQUEST OF JERUSALEM
Meanwhile, Sayyiduna Amr ibn As (radi Allahu anhu) was laying siege to Jerusalem. Sayyiduna Khalid, Sayyiduna Abu Ubaidah and other Sahaba (radi Allahu anhumul ajma'in) also joined him. The Christians had little hope and decided to give in. They also suggested that the keys of Jerusalem be given to Sayyiduna Umar (radi Allahu anhu) himself personally. Sayyiduna Umar (radi Allahu anhu) went to Jerusalem. An agreement was signed that guaranteed the safety of the city and the safety of the Christians.
A Persian non-Muslim, named Firoz and nicknamed "Abu Lulu," complained to Sayyiduna Umar (radi Allahu anhu) about his master, Sayyiduna Mughirah bin Shuba (radi Allahu anhu), who imposed tax on him. Sayyiduna Umar (radi Allahu anhu) told Firoz that the tax was reasonable. This made Firoz angry.
The next day, during the Fajr Salaah, he stabbed Sayyiduna Umar (radi Allahu anhu) 6 times in the back, severely wounding the Caliph. Sayyiduna Umar (radi Allahu anhu) passed away 3 days later in 23 A.H. He was 63 years old. He ruled the Islamic State for 10 years, 6 months and 4 days.
In a short space of 10 years, Sayyiduna Umar (radi Allahu anhu) had been well-known for his outstanding achievements and reforms in Islam. Some of these reforms were:-
1. He established the "Baitul Maal" (People's treasury for the state and public).
2. Judicial courts of Justice were set in the country. Judges and Magistrates handled all cases.
3. Establishment of an army headquarters for the defence of the country.
4. Construction of roads and canals.
5. Schools were established. Salaries for Imams, Mu'azzins and Ustaads were organized.
6. Masjids were improved and built in Makkatul Mukarramah and Madinatul Munawwarah. This included facilities for the Haajis.
7. Police Stations and prisons were built.
8. Establishment of the first Islamic Lunar calendar beginning from the Hijrah.
9. Proper weights and measures introduced.
10. Population census established.
11. Built orphanages and welfare homes.
12. Established proper punishment system and banned slavery.
Simplicity and devotion were the main characters of Sayyiduna Umar (radi Allahu anhu). He used to wear clothes that had many patches and yet received Governors, convoys and diplomats. He took just enough allowance from the State to have a simple meal and wear simple clothes. At times he was very poor. He used to visit the old people and sick and even do their house work. He used to visit the houses of the soldiers and inquire about their families. He stayed awake at night in Salaah and often kept Fast. He always supported and upheld the cause of Islam, with his wisdom, energy, dynamism, bravery and little wealth.