RUHR, a river of Germany, 142 m. long, an important right bank tributary of the lower Rhine. It rises on the side of the Winterberg in the Sauerland, at about 2,000 ft. above the sea. It flows north and then west in a deep, well-wooded valley past the town of Arnsberg. Shortly after reaching Neheim it bends south-west, and courses through the important mining district of the Ruhr coalfield around Hagen. Hence in a tortuous course it passes Witten, Steele, Kettwig and Millheim, and joins the Rhine at Ruhrort. The river is navigable from Witten down wards, by the aid of eleven locks. Its chief affluents are the Mahne (right) and Lenne (left).
French Occupation.—Though the occupation of the left bank of the Rhine arranged for in the Treaty of Versailles included the bridge-head at Cologne, and thus practically touched the Ruhr district, the French were not satisfied from a military point of view, as the "Westphalian basin" was the hub of the German iron and steel industry. In March 1921 the French extended the occupation to Duisburg, Ruhrort and Diisseldorf, containing 5,00o sq.km. and 877,000 inhabitants, as a sanction for Germany's refusing the Paris reparation proposals; another 37,700 sq.km. with 3,191,000 inhabitants were occupied during 1923-24, when they controlled almost the entire Ruhr district.
Before the World War most of the Lorraine iron and steel works were owned by or closely affiliated with concerns in the Ruhr. The low grade iron ore of Lorraine, apart from the quantities used on the spot went to the blast furnaces of the Ruhr. Of 21,100,000 tons mined, 3,100,000 tons went to the Ruhr. On the other hand the coke of the Ruhr was needed for the smelting of Lorraine ores, whilst the finished iron and steel goods of Lorraine found their market in south-western Germany.
The re-annexation of Alsace–Lorraine and the retirement of Luxembourg from the German customs union reduced Germany's home supply of iron ore to about 2o% of its former size. At the same time France became the greatest iron ore producing country of Europe; moreover she controlled the well equipped iron and steel mills in Lorraine, expropriating the German iron and steel masters. She also temporarily annexed the Saar mines, partly in the hope of getting coke for her iron industries. As the Saar coal did not coke well, special clauses were inserted in the Treaty of Peace, guaranteeing to France (and to the other Allies) a regular supply of the Ruhr coal and coke at statutory prices.
Political pressure apart, however, the German coalmasters held the winning hand. Compensation from the German govern
ment enabled them to erect new iron and steel works on the Ruhr, which could easily be run with high-grade Swedish or Spanish ore or with the enormous quantities of scrap available after the war. The low grade Lorraine ore, on the other hand, had either to be smelted locally or sent to the Ruhr. Smelting in Lorraine de pended on the regular supply of Ruhr coke. And the export of finished products depended mainly on German markets which were open to France without duty for five years only (within the limits of Alsace–Lorraine's pre-war sales to Germany). Thus those who controlled the Ruhr coal really controlled the Lorraine iron and steel industry.
As early as the Conference of Spa (192o) when Germany had fallen short on coal deliveries, the Allies presented her with an ultimatum, which threatened the occupation of the Ruhr in case of non-acceptance. Though this extension of the area of occupation was an arbitrary act, the German Government gave way. From this moment the French began to use this threat of an extension of the occupation as a weapon in the struggle about reparation. When the German Government refused the proposals of the Paris Conference (Jan. 29, 1921) they occupied Dusseldorf, Ruhrort and Duisburg, and continued the occupation after Germany had accepted the London ultimatum of May 5, 1921.
On Dec. 26, 1922, the Reparation Commission under French pressure announced that Germany had fallen short on the delivery of 20,000 cu.m. of boards and of 130,000 telegraph poles, the total averaging but a few million marks; a few days later a similar shortcoming in coal-deliveries variously estimated at I I to 15.6%, was declared. Against the vote of the British delegates the Repa ration Commission came to the conclusion that Germany's short comings had been "intentional" (manquement volontaire), con stituting a case under Annex II § 18, which permitted the Allied and Associated Powers to take "such other measures as the re spective Governments may determine to be necessary in the cir cumstances." The French and Belgian Governments decided to send a commission of engineers into the Ruhr, to control the activities of the Coal Syndicate and the carrying out of the de liveries as, in their opinion the coal mine owners were trying to sabotage the Treaty. This technical mission, in which Italy was to participate, but not Great Britain, was accompanied by a military force, though military occupation was not intended.