History of the German flag dates back to the Roman Empire.
Germania Inferior - the territory west of the Rhine and Germania Superior - the territory south of the Danube were Roman provinces. Magna Germania territory was free of the Germanic tribes. After the demise of the Western Roman Empire in 476 began to gradually create Frankish Empire.
Coronation of the most important Frankish ruler Charlemagne as emperor by Pope Leo III. in Rome on 25.12.800 goes back to thousand year history of the Holy Roman Empire of the German until 1806. Imperial flag to show in golden field of black eagle with red beak and claws. Flag Frankish empire appear on the white box of the same black eagle with red beak and claws. An Eagle was once a symbol of the Roman Empire and was part of the Roman vexillies. The war flag Holy Roman Empire of the German Nation was a white cross on a red field. Since 1401 changed the imperial flag in the form of an eagle with two heads. In 1437 the imperial flag started adding coats of arms of the sovereign.
In 1806 Napoleon forced the Habsburg Emperor Franz Composition imperial crown. On the side of Napoleon joined 36 German States Conference of Rhine except Austria, Prussia, Hesse and Brunswick. After the Battle of Nations in the period 1815 - 1848 the German Confederation was used imperial flag with a black two-headed eagle with red beaks and claws on golden field in the years 1848 - 1850 used black - red - yellow tricolour.
Discrepancies between Austria and Prussia in the war escalated the conflict and the subsequent division of the South German conference led by Austria and northern Germany conference led by Prussia and President Wilhelm I. -The Prussian king. On 07.01.1867 was adopted a new constitution and flag black - white - red tricolour, which is a combination of black - white flag of Prussia and the common red - white flag Hansa - Association of Free and Hansa cities. Black colour symbolizes the black and dark past. White represented a bright and shining future. Red meant the struggle for national unity. For the identification of commercial and warships were used trade and war flag. They took the flag and II. German Empire in the years 1871 - 1919, which arose after the victory over Napoleon III of Prussia and disappeared defeat in the First World War.
In 1919 in Weimar was accepted democratic federal constitution with a new flag. Black - red - yellow tricolour, they used the revolutionaries in Germany struggle for equality, fraternity and liberty.
Hard to liquidation, surrender conditions caused the landslide victory of the National Socialists, led by Adoph Hitler, who sought to create III. German Empire. During that period, in the years 1933 - 1945 was soon replaced by the Weimar flag flag II. German Empire and from 1935 to 1945 at a length of 10 years, began using red flag with a swastika in a white circle. Red symbolizes social ideas, white ring is pure Aryan race and black swastika - swastika symbolized the fight and desire for victory productive Aryan man.
After the II. World War II, the victorious powers divided Germany into four zones. American, British and French gradually merged in 1949 into one of the Federal Republic of Germany with black - red - yellow flag. Of the Soviet zone was called since 1959 German Democratic Republic and used black - red - yellow flag with a creative emblem that symbolizes the unity of the working people in industry, science and agriculture. After the fall of communism, was in the 1990 reunification of Germany and a common German flag.
The two-part video about the history of Germany in German flag you can find on youtube:
