Tributary state in the context of "Suzerainty"

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).

Serbia, officially the Republic of Serbia, is a landlocked country in Southeast and Central Europe. Located in the Balkans, it borders Hungary to the north, Romania to the northeast, Bulgaria to the southeast, North Macedonia to the south, Croatia to the northwest, Bosnia and Herzegovina to the west, and Montenegro to the southwest. Serbia also claims to share a border with Albania through the disputed territory of Kosovo. Serbia has about 6.6 million inhabitants, excluding Kosovo. Serbia's capital, Belgrade, is also the largest city in the country.

Continuously inhabited since the Paleolithic age, the territory of modern-day Serbia faced Slavic migrations in the 6th century. Several regional states were founded in the Early Middle Ages and were at times recognised as tributaries to the Byzantine, Frankish and Hungarian kingdoms. The Serbian Kingdom obtained recognition by the Holy See and Constantinople in 1217, reaching its territorial apex in 1346 as the Serbian Empire. By the mid-16th century, the Ottoman Empire annexed the entirety of modern-day Serbia; their rule was at times interrupted by the Habsburg Empire, which began expanding towards Central Serbia from the end of the 17th century while maintaining a foothold in Vojvodina. In the early 19th century, the Serbian Revolution established the nation-state as the region's first constitutional monarchy, which subsequently expanded its territory.

Algeria, officially the People's Democratic Republic of Algeria, is a country in the Maghreb region of North Africa. It is bordered to the northeast by Tunisia; to the east by Libya; to the southeast by Niger; to the southwest by Mali, Mauritania, and Western Sahara; to the west by Morocco; and to the north by the Mediterranean Sea. The capital and largest city is Algiers, located in the far north on the Mediterranean coast.

Algeria has been at the crossroads of numerous cultures and civilisations for millennia, including the Phoenicians, Numidians, Romans, Vandals, and Byzantine Greeks. Its modern identity is rooted in centuries of Arab Muslim migration since the seventh century and the subsequent Arabisation of indigenous Berber populations. Following a succession of Islamic Arab and Berber dynasties between the eighth and 15th centuries, the Regency of Algiers was established in 1516 as a largely independent tributary state of the Ottoman Empire. After nearly three centuries as a major power in the Mediterranean, the country was invaded by France in 1830 and formally annexed in 1848, though it was not fully conquered and pacified until 1903. French rule brought mass European settlement that displaced the local population, which was reduced by up to one-third due to warfare, disease, and starvation. The Sétif and Guelma massacre in 1945 catalysed local resistance that culminated in the outbreak of the Algerian War in 1954. Algeria gained independence in 1962. It descended into a bloody civil war from 1992 to 2002, remaining in an official state of emergency until the 2010–2012 Algerian protests during the Arab Spring.

A client state, in the context of international relations, is an umbrella term that broadly refers to any state economically, politically, and militarily subordinated to a more powerful controlling state. It typically describes a bilateral relationship that is mutually beneficial, characterized by different but shared obligations.

Variants of a client state are associated state, dominion, condominium, self-governing colony, neo-colony, protectorate, puppet state, satellite state, vassal state and tributary state.

The Ottoman Empire had a number of tributary and vassal states throughout its history. Its tributary states would regularly send tribute to the Ottoman Empire, which was understood by both states as also being a token of submission. In exchange for certain privileges, its vassal states were obligated to render support to the Ottoman Empire when called upon to do so. Some of its vassal states were also tributary states.

These client states, many of which could be described by modern terms such as satellite states or puppet states, were usually on the periphery of the Ottoman Empire under suzerainty of the Sublime Porte, over which direct control was not established. The Ottoman Empire maintained relationships with various states, some of which were under their direct rule (provinces) and others that were vassal states or tributary states, meaning they recognized Ottoman suzerainty but retained a degree of autonomy.

The First Sino-Japanese War (25 July 1894 – 17 April 1895), or the First China–Japan War, was a conflict between the Qing dynasty of China and the Empire of Japan primarily for influence over Korea. In Chinese it is commonly known as the Jiawu War. After more than six months of unbroken successes by Japanese land and naval forces and the loss of the ports of Lüshunkou (Port Arthur) and Weihaiwei, the Qing government sued for peace in February 1895 and signed the unequal Treaty of Shimonoseki two months later, ending the war.

In the late 19th century, Korea remained one of the Qing tributary states, while Japan viewed it as a target of imperial expansion. In June 1894, the Qing government, at the request of the Korean emperor Gojong, sent 2,800 troops to aid in suppressing the Donghak Peasant Revolution. The Japanese considered this a violation of the 1885 Convention of Tientsin, and sent an expeditionary force of 8,000 troops, which landed at Incheon. This army moved to Seoul, seized the Korean emperor, and set up a pro-Japanese government on 23 July 1894 in the occupation of Gyeongbokgung. The Qing government decided to withdraw its troops, but rejected recognition of the pro-Japanese government, which had granted the Imperial Japanese Army the right to expel the Qing's Huai Army from Korea. About 3,000 Qing troops still remained in Korea, and could be supplied only by sea; on 25 July, the Japanese Navy won the Battle of Pungdo and sank the steamer Kowshing, which was carrying 1,200 Qing reinforcements. A declaration of war followed on 1 August.