Marriage of state in the context of "Expansion of Macedonia under Philip II"

Under the reign of Philip II (359–336 BC), the ancient kingdom of Macedonia, initially at the periphery of classical Greek affairs, came to dominate Ancient Greece in the span of less than 25 years, largely thanks to the character and policies of its king. In addition to utilising effective diplomacy and marriage alliances to achieve his political aims, Philip II was responsible for reforming the ancient Macedonian army into an effective fighting force. The Macedonian phalanx became the hallmark of the Macedonian army during his reign and the subsequent Hellenistic period. His army and engineers also made extensive use of siege engines. Chief among Philip's Thracian enemies was the ruler Kersebleptes, who may have coordinated a temporary alliance with Athens. In a series of campaigns stretching from 356 to 340 BC, Philip II managed to ultimately subjugate Kersebleptes as a tributary vassal, conquering much of Thrace in the process. Philip II also fought against the Illyrian king Bardylis, who threatened Macedonia proper, and against Grabos II and Pleuratus in Illyria (centred in modern-day Albania). In his newly conquered territories, he founded new cities such as Philippi, Philippopolis (modern Plovdiv, Bulgaria), Herakleia Sintike (Pirin Macedonia, Bulgaria), and Herakleia Lynkestis (modern Bitola, North Macedonia).

Philip II eventually campaigned against the city-state of Athens and her allies in the Aegean region, as well as Thebes after the decline of its hegemony in mainland Greece. In the defence of the Amphictyonic League of Delphi and in conjunction with the Thessalian League, Macedonia became a key player in the Third Sacred War (356–346 BC), defeating the Phocians, commanded by Onomarchus, at the Battle of Crocus Field in 352 BC. While poised to launch a direct assault on Athens in 346 BC, the Macedonian king was met with an Athenian embassy that arranged the Peace of Philocrates. As a result, Macedonia and Athens became allies, yet Athens was forced to relinquish its claims to the city of Amphipolis (in modern-day Central Macedonia).

The sack of Rome in 455 was carried out by the Vandals led by their king Gaiseric.

A 442 treaty between the Western Roman Empire and Vandal Kingdom included a marriage of state between the daughter of Roman Emperor Valentinian III and the son of Gaiseric. Valentinian's successor Petronius Maximus violated the treaty by marrying his son to Valentinian's daughter, and Gaiseric retaliated with an invasion of Italy. Maximus did not organise a defence of Rome and was lynched by a Roman mob while trying to escape the city. Pope Leo I convinced Gaiseric to avoid the use of violence against residents of the city. The Vandals looted Rome for two weeks, causing widespread destruction to the city, stripping it of most of its valuables, and taking some residents as slaves. Maximus' successor Avitus had little support which led to the outbreak of the Roman civil war of 456.

The Marriage Treaty, or Anglo-Portuguese Treaty, was a treaty of alliance that was agreed between the Kingdom of England and the Kingdom of Portugal and concluded on 23 June 1661.

It led to the marriage of Charles II of England and Catherine of Braganza, the daughter of John IV of Portugal. It was a marriage of state, as was common in the era.

Sophia Dorothea of Brunswick-Lüneburg-Celle (15 September 1666 – 13 November 1726) was the repudiated wife of future King George I of Great Britain. The union with George, her first cousin, was a marriage of state, arranged by her father George William, her father-in-law the Elector of Hanover, and her mother-in-law, Electress Sophia of Hanover, first cousin of King Charles II of England.

Sophia Dorothea is best remembered for her alleged affair with Count Philip Christoph von Königsmarck that led to her being imprisoned in the Castle of Ahlden for the last thirty years of her life.