The Rashidun Caliphate Army or Rashidun army was the primary military body of the Rashidun Caliphate's armed forces during the Muslim conquests of the 7th century, serving alongside the Rashidun Navy. The Rashidun army maintained a high level of discipline, strategic prowess, and organization.

In its time, the Rashidun army was the most powerful and effective military forces in the world. The size of the Rashidun army was initially 13,000 troops in 632, but as the Caliphate expanded, the army gradually grew to 100,000 troops by 657. The two most successful generals of the Rashidun army were Khalid ibn al-Walid, who conquered Persian Mesopotamia and conquered Roman Syria, and 'Amr ibn al-'As, who conquered Roman Egypt.

Only Muslims were allowed to join the Rashidun army as regular troops. During the Ridda wars in the reign of Caliph Abu Bakr, the army mainly consisted of the corps from Madinah, Mecca and Taif. Later on during the conquest of Iraq in 633 many bedouin corps were recruited in the forces as regular troops. During the Islamic conquest of Sassanid Persia (633-656), some 12,000 elite Persian troops converted to Islam and served later on during the wholescale invasion of the empire. During the Muslim conquest of Roman Syria (633-638) some 4,000 Greek Byzantine soldiers under their commander Joachim (later Abdullah Joachim) converted to Islam and served as regular troops in the conquest of both Anatolia and Egypt. During the conquest of Egypt (641-644), Coptic converts to Islam were recruited and eased the conquest. During the conquest of North Africa, Berber converts to Islam were recruited as regular troops, who later made the bulk of the Rashidun army and later the Ummayad army in Africa.

The Rightly Guided Caliphs or The Righteous Caliphs (الخلفاء الراشدون al-Khulafā’u r-Rāshidūn) is a term used in Sunni Islam to refer to the first four Caliphs who established the Rashidun Caliphate. The concept of "Rightly Guided Caliphs" originated with the Abbasid Dynasty. It is a reference to the Sunni tradition, "Hold firmly to my example (sunnah) and that of the Rightly Guided Caliphs" (Ibn Majah, Abu Dawood).

The first four Caliphs who ruled after the death of Muhammad are often quoted as the Khulafah Rashidun.

The Rashidun were either elected by a council (see The election of Uthman and Islamic democracy) or chosen based on the wishes of their predecessor. In the order of succession, the rashidun were:

Hasan ibn Ali was appointed as Caliph in 661 following the death of Ali and is also regarded as a righteous ruler by Sunni Muslims, although he was recognized by only half of the Islamic state and his rule was challenged and eventually ended by the Governor of Syria, Muawiyah ibn Abi Sufyan.

The Rashidun Caliphate (Arabic: الخلافة الراشدية‎ al-khilāfat ar-Rāshidīyah), (c. 632-661) comprising the first four caliphs in Islam's history, was founded after Muhammad's death in 632 (Year 10 A.H. in the Islamic calendar). At its height, the Caliphate extended from the Arabian Peninsula, to the Levant, Caucasus and North Africa in the west, to the Iranian highlands and Central Asia in the east. At its greatest extent it was one of the largest empires in history. It is also known as the Patriarchal Caliphate.

After Muhammad's death in 632, the Medinan Ansar debated which of them should succeed him in running the affairs of the Muslims while Muhammad's household was busy with his burial. Umar (a Quraish) and Abu Ubaidah ibn al-Jarrah pledged their loyalty to Abu Bakr, with the Ansar and the Quraish soon following suit. Abu Bakr thus became the first Khalifa Rasul Allah (Successor of the Messenger of God), and embarked on campaigns to propagate Islam. First, though, he would have to subdue the Arabian tribes which had gone back on their oaths of allegiance to Islam and the Islamic community. As a Khalifa or Caliph he was not a monarch and never claimed such a title nor did his three successors do so.