Mercenary in the context of "Alan fitz Flaad"

A declaration of war is a formal act by which one state announces existing or impending war activity against another. The declaration is a performative speech act (or the public signing of a document) by an authorized party of a national government, in order to create a state of war between two or more states.

The legality of who is competent to declare war varies between nations and forms of government. In many nations, that power is given to the head of state or sovereign. In other cases, something short of a full declaration of war, such as a letter of marque or a covert operation, may authorise war-like acts by privateers or mercenaries. The official international protocol for declaring war was defined in the Hague Convention (III) of 1907 on the Opening of Hostilities.

The Normans (Norman: Normaunds; French: Normands; Latin: Nortmanni/Normanni) were a population arising in the medieval Duchy of Normandy from the intermingling between Norse Viking settlers and locals of West Francia. The Norse settlements in West Francia followed a series of raids on the French northern coast mainly from what is now Denmark, although some also sailed from Norway and Sweden. These settlements were finally legitimized when Rollo, a Scandinavian Viking leader, agreed to swear fealty to King Charles III of West Francia following the siege of Chartres in 911, leading to the formation of the County of Rouen. This new fief, through kinship in the decades to come, would expand into what came to be known as the Duchy of Normandy. The Norse settlers, whom the region as well as its inhabitants were named after, adopted the language, religion, social customs and martial doctrine of the West Franks but their offspring nonetheless retained many of their traits, notably their mercenary tendencies and their fervour for adventures. The intermixing between Norse folk and native West Franks in Normandy produced an ethnic and cultural "Norman" identity in the first half of the 10th century, an identity which continued to evolve over the centuries.

The Norman dynasty had a major political, cultural and military impact on medieval Europe and the Near East. The Normans were historically famed for their martial spirit, and eventually for their Catholic piety as adherents of the Catholic orthodoxy of the Romance community. The original Norse settlers adopted the Gallo-Romance language of the Frankish land they settled, with their Old Norman dialect becoming known as Norman, Normaund or Norman French, an important literary language which is still spoken today in parts of mainland Normandy (Cotentinais and Cauchois dialects) and the nearby Channel Islands (Jèrriais and Guernésiais). The Duchy of Normandy, which arose from the Treaty of Saint-Clair-sur-Epte, was a great fief of medieval France. The Norman dukes exercised independent control of their holdings in Normandy, while at the same time being vassals owing fealty to the King of France, and under Richard I of Normandy (byname Richard sans Peur, meaning "Richard the Fearless"), the duchy was forged into a cohesive and formidable principality in feudal tenure.

The Hellenistic armies is a term that refers to the various armies of the successor kingdoms to the Hellenistic period, emerging soon after the death of Alexander the Great in 323 BC, when the Macedonian empire was split between his successors, known as the Diadochi (Ancient Greek: Διάδοχοι).

Initially, the Hellenistic armies were very similar to those commanded by Alexander the Great, but during the era of the Epigonoi (Ἐπίγονοι, "Successors") the differences became obvious, with the Diadochi growing to favor large masses of soldiers rather than smaller, well-trained ones, and weight was valued over maneuverability. The limited availability of Greek conscripts in the east led to an increasing dependence on mercenary forces, whereas the Hellenistic armies in the west were continuously involved in wars, which soon exhausted local manpower, paving the way for Roman supremacy in the region.

There is evidence of mercenaries (misthophoroi (plural), misthios (singular male), misthia (singular female) in Greek) being hired in Ancient Greece from the 6th century BC. The tyrants of that time hired bodyguards from other city-states. It is not known if earlier Aegean armies and navies, such as the Minoans and Mycenaeans, used mercenaries.

Mercenary troops from Caria and Ionia are known to have fought with Psamtik I against the Assyrians. These were the "bronze men from the sea" whose arrival in Egypt, according to Herodotus, was foretold to Psamtik by an oracle. They entered the country as raiders but Psamtik made a truce with them and hired them to his cause. Afterwards, he granted land to them alongside the Nile and they are traditionally held to have been the first Greeks to settle in Egypt.

The Ten Thousand (Ancient Greek: οἱ Μύριοι, hoi Myrioi) were a force of mercenary units, mainly Greeks, employed by Cyrus the Younger to attempt to wrest the throne of the Persian Empire from his brother, Artaxerxes II. Their march to the Battle of Cunaxa and back to Greece (401–399 BC) was recorded by Xenophon, one of their leaders, in his work Anabasis.

A regular army is the official army of a state or country (the official armed forces), contrasting with irregular forces, such as volunteer irregular militias, private armies, mercenaries, etc. A regular army usually has the following:

• a standing army, the permanent force of the regular army that is maintained under arms during peacetime.
• a military reserve force that can be mobilized when needed to expand the effectiveness of the regular army by complementing the standing army.

Irregular military is any military component distinct from a country's regular armed forces, representing non-standard militant elements outside of conventional governmental backing. Irregular elements can consist of militias, private armies, mercenaries, or other non-state actors, though no single definition exists beyond exclusion from national service. Without standard military unit organization, various more general names are often used; such organizations may be called a troop, group, unit, column, band, or force. Irregulars are soldiers or warriors that are members of these organizations, or are members of special military units that employ irregular military tactics. This also applies to irregular infantry and irregular cavalry units.

Irregular warfare is warfare employing the tactics commonly used by irregular military organizations. This often overlaps with asymmetrical warfare, avoiding large-scale combat and focusing on small, stealthy, hit-and-run engagements.

The Byzantine army was the primary military body of the Byzantine armed forces, serving alongside the Byzantine navy. A direct continuation of the Eastern Roman army, shaping and developing itself on the legacy of the late Hellenistic armies, it maintained a similar level of discipline, strategic prowess and organization. It was among the most effective armies of western Eurasia for much of the Middle Ages. Over time the cavalry arm became more prominent in the Byzantine army as the legion system disappeared in the early 7th century. Later reforms reflected some Germanic and Asian influences—rival forces frequently became sources of mercenary units, such as the Huns, Cumans, Alans and (following the Battle of Manzikert) Turks, meeting the Empire's demand for light cavalry mercenaries. Since much of the Byzantine military focused on the strategy and skill of generals utilizing militia troops, heavy infantry were recruited from Frankish and later Varangian mercenaries.

From the 6th to the 12th centuries, the Byzantine army was among the most powerful and effective military forces in the world – neither Middle Ages Europe nor (following its early successes) the fracturing Caliphate could match the strategies and the efficiency of the Byzantine army. Restricted to a largely defensive role in the 7th to mid-9th centuries, the Byzantines developed the theme system to counter the more powerful Caliphate. From the mid-9th century, however, they gradually went on the offensive, culminating in the great conquests of the 10th century under a series of soldier-emperors such as Nikephoros II Phokas, John Tzimiskes and Basil II. The army they led was less reliant on the militia of the themes; it was by now a largely professional force, with a strong and well-drilled infantry at its core and augmented by a revived heavy cavalry arm. With one of the most powerful economies in the world at the time, the Empire had the resources to put to the field a powerful host when needed, in order to reclaim its long-lost territories.