Grand Duchy of Hesse in the context of "Landgraviate of Hesse-Darmstadt"

Mainz (German: [maɪnts] ; see below) is the capital and largest city of the German state of Rhineland-Palatinate, and with around 223,000 inhabitants, it is Germany's 35th-largest city. It lies in the Rhine-Main Metropolitan Region—Germany's second-largest metropolitan region after Rhine-Ruhr—which also encompasses the cities of Frankfurt am Main, Wiesbaden, Darmstadt, Offenbach am Main, and Hanau.

Mainz is located at the northern end of the Upper Rhine Plain, on the left bank of the Rhine. It is the largest city of Rhenish Hesse, a region of Rhineland-Palatinate that was historically part of Hesse, and is one of Germany's most important wine regions because of its mild climate. Mainz is connected to Frankfurt am Main by the Rhine-Main S-Bahn rapid transit system. Before 1945, Mainz had six boroughs on the other side of the Rhine (see: de:Rechtsrheinische Stadtteile von Mainz). Three have been incorporated into Wiesbaden (see: de:AKK-Konflikt), and three are now independent.

The proclamation of the German Empire, also known as the Deutsche Reichsgründung, took place on January 18, 1871 after the joint victory of the German states in the Franco-Prussian War. As a result of the November Treaties of 1870, the southern German states of Baden, Hesse-Darmstadt, with their territories south of the Main line, Württemberg and Bavaria, joined the Prussian-dominated "North German Confederation" on 1 January 1871. On the same day, the new Constitution of the German Confederation came into force, thereby significantly extending the federal German lands to the newly created German Empire. The Day of the founding of the German Empire, January 18, became a day of celebration, marking when the Prussian King William I was proclaimed German Emperor at the Palace of Versailles, outside Paris, France.

Grand duke (feminine: grand duchess) is a European hereditary title, used either by certain monarchs or by members of certain monarchs' families. The title is used in some current and former independent monarchies in Europe, particularly:

• in present-day Luxembourg, the last surviving Grand Duchy
• historically by the sovereigns of former independent countries, such as Tuscany (from 1569 to 1860, now part of Italy)
• in Baden, Hesse, Oldenburg, Mecklenburg-Schwerin, Mecklenburg-Strelitz and Saxe-Weimar-Eisenach (officially simply the Grand Duchy of Saxony) – grand duchies from 1815 to 1918, and all now part of Germany
• formerly also in some countries in Northern Europe, such as the Grand Duchy of Finland or the Grand Duchy of Lithuania
• currently by claimants to the Russian Imperial Throne (eg. Grand Duke George Mikhailovich of Russia)

The Rhine Province (German: Rheinprovinz), also known as Rhenish Prussia (Rheinpreußen) or synonymous with the Rhineland (Rheinland), was the westernmost province of the Kingdom of Prussia and the Free State of Prussia, within the German Reich, from 1822 to 1946. It was created from the provinces of the Lower Rhine and Jülich-Cleves-Berg. Its capital was Koblenz, with the provincial assembly meeting in Düsseldorf. In 1939 it had 8 million inhabitants. The Province of Hohenzollern was militarily associated with the Oberpräsident of the Rhine Province. Also, for a short period of time, the Province of Hohenzollern was indirectly and de facto controlled by the Rhine Province.

The Rhine Province was bounded on the north by the Netherlands, on the east by the Prussian provinces of Westphalia and Hesse-Nassau, and the grand duchy of Hesse-Darmstadt, on the southeast by the Palatinate (a district of the Kingdom of Bavaria), on the south and southwest by Lorraine, and on the west by Luxembourg, Belgium and the Netherlands.

The People's State of Hesse (German: Volksstaat Hessen) was one of the constituent states of Germany from 1918 to 1945, as the successor to the Grand Duchy of Hesse (German: Großherzogtum Hessen) after the defeat of the German Empire in World War I, on the territory of the current German states of Hesse and the Rhineland-Palatinate. The State was established after Grand Duke Ernest Louis was deposed on 9 November 1918. The term "People's State" referred to the fact that the new state was a Republic (rather than implying that it was a socialist state) and was used in the same manner as the term Free State, which was employed by most of the other German States in this period.

Like the Grand Duchy, the capital was Darmstadt and the state consisted of provinces Upper Hesse (German: Oberhessen, capital Gießen), Starkenburg (capital Darmstadt) and Rhenish Hesse (German: Rheinhessen, capital Mainz). The area of the state was 7,692 km²; it had 1,347,279 inhabitants in 1925. Around two-thirds professed Protestantism, the other third were Roman Catholics.

Rhenish Hesse or Rhine Hesse (German: Rheinhessen, pronounced [ʁaɪnˈhɛsn̩]) is a region and a former government district (Regierungsbezirk) in the German state of Rhineland-Palatinate. It is made up of territories west of the Upper Rhine river that were part of the Grand Duchy of Hesse and its successor in the Weimar Republic, the People's State of Hesse from 1816 to 1945. The hilly countryside is largely devoted to vineyards, comprising the Rheinhessen wine region.

The Province of Hesse-Nassau (German: Provinz Hessen-Nassau) was a province of the Kingdom of Prussia from 1868 to 1918, then a province of the Free State of Prussia until 1944.

Hesse-Nassau was created as a consequence of the Austro-Prussian War of 1866 by combining the previously independent Hesse-Kassel (or Hesse-Cassel), the Duchy of Nassau, the Free City of Frankfurt, areas gained from the Kingdom of Bavaria, and areas gained from the Grand Duchy of Hesse (including part of the former Landgraviate of Hesse-Homburg from Hesse-Darmstadt). These regions were combined to form the province Hesse-Nassau in 1868 with its capital in Kassel and redivided into two administrative regions: Kassel and Wiesbaden. The largest part of the province surrounded the province of Upper Hesse in the Grand Duchy of Hesse (People's State of Hesse from 1918).

The Constitution of the German Confederation (German: Verfassung des Deutschen Bundes) or November Constitution (Novemberverfassung) was the constitution of the German federal state at the beginning of the year 1871. It was enacted on January 1, 1871. This is a slightly changed version of the Constitution of the North German Confederation; it is not to be confused with the constitutional laws of the German Confederation of 1815.

The Constitution of the German Confederation of 1871 incorporated agreements between the North German Confederation and some of the South German states that joined the Confederation: with Baden and Hesse-Darmstadt, but not Bavaria and Württemberg. The new constitution appeared on 31 December 1870 in the Bundesgesetzblatt des Norddeutschen Bundes (North German Federal Law Gazette) and came into effect the following day.