Oath of allegiance in the context of "Military oath"

The Pereiaslav Agreement or Pereyaslav Agreement (Ukrainian: Переяславська рада, romanized: Pereiaslavska Rada, lit. 'Pereiaslav Council', Russian: Переяславская рада) was an official meeting that convened for a ceremonial pledge of allegiance by Zaporozhian Cossacks to Russian tsar Alexis (r. 1645–1676) in the town of Pereiaslav in central Ukraine, in January 1654. The ceremony took place concurrently with ongoing negotiations that started on the initiative of Hetman Bohdan Khmelnytsky to address the issue of the Cossack Hetmanate with the ongoing Khmelnytsky Uprising against the Polish–Lithuanian Commonwealth and which concluded the Treaty of Pereiaslav (also known as the March Articles). The treaty itself was finalized in Moscow in April 1654 (in March according to the Julian calendar).

Khmelnytsky secured the military protection of the Tsardom of Russia in exchange for allegiance to the tsar. An oath of allegiance to the Russian monarch from the leadership of the Cossack Hetmanate was taken, shortly thereafter followed by other officials, the clergy and the inhabitants of the Hetmanate swearing allegiance. The exact nature of the relationship stipulated by the agreement between the Hetmanate and Russia is a matter of scholarly controversy. The council of Pereiaslav was followed by an exchange of official documents: the March Articles (from the Cossack Hetmanate) and the tsar's declaration (from Russia).

An oath of office is an oath or affirmation a person takes before assuming the duties of an office, usually a position in government or within a religious body, although such oaths are sometimes required of officers of other organizations. Such oaths are often required by the laws of the state, religious body, or other organization before the person may actually exercise the powers of the office or organization. It may be administered at an inauguration, coronation, enthronement, or other ceremony connected with the taking up of office itself, or it may be administered privately. In some cases it may be administered privately and then repeated during a public ceremony.

Some oaths of office are statements of allegiance and loyalty to a constitution or other legal text or to a person or office-holder (e.g., an oath to support the constitution of the state, or of loyalty to the king or queen) (see Oath of allegiance). Under the laws of a state, it may be considered treason or a high crime to betray a sworn oath of office. In many cases, the oath is performed using an oath book, typically religious scripture such as the Bible.

Naturalization (or naturalisation) is the legal act or process by which a non-national of a country acquires the nationality of that country after birth. The definition of naturalization by the International Organization for Migration of the United Nations excludes citizenship that is automatically acquired (e.g. at birth) or is acquired by declaration. Naturalization usually involves an application or a motion and approval by legal authorities. The rules of naturalization vary from country to country but typically include a promise to obey and uphold that country's laws and taking and subscribing to an oath of allegiance, and may specify other requirements such as a minimum legal residency and adequate knowledge of the national dominant language or culture. To counter multiple citizenship, some countries require that applicants for naturalization renounce any other citizenship that they currently hold, but whether this renunciation actually causes loss of original citizenship, as seen by the host country and by the original country, will depend on the laws of the countries involved. Naturalization is politicized due to the reshaping of the electorate of the country.

Bayʿah (Arabic: بَيْعَة, "Pledge of allegiance"), in Islamic terminology, is an oath of allegiance to a leader. It is known to have been practiced by the Islamic prophet Muhammad. In Bedouin culture it was a procedure for choosing the leader of the tribe, and is sometimes taken under a written pact given on behalf of the subjects by leading members of the tribe with the understanding that as long as the leader abides by certain requirements towards his people, they are to maintain their allegiance to him. Bayʿah is still practiced in countries such as Saudi Arabia and Sudan. In Morocco, bayʿah is one of the foundations of the monarchy.