Ravel's first journey outside France took the form of a seven-week canal trip during June and July 1905, on board the yacht Aimée which belonged to Misia and Alfred Edwards. Their route took them through Belgium, Holland and Germany, and Ravel described his experiences in a series of letters to Maurice Delage (Chalupt,  p.29-43).
Ravel joined the expedition at Soissons, and other guests already on board included the painters Pierre Laprade and Pierre Bonnard. For Ravel the holiday provided an immense relief from the furore which had broken out over his exclusion from the Prix de Rome, and also from an intensive period of work to complete the Introduction et allegro.
They travelled northwards through the Ardennes and into Belgium, stopping at Liége, then to Holland with a week in Amsterdam; then up the Rhine into Germany (Düsseldorf, Köln, Koblenz and Frankfurt); then back into Holland (Dordrecht, Veere, Middelburg and Vlissingen) and along the Belgian coast (Oostende); finally returning to France at Le Havre.
Ravel's first encounter with Germany was made by boat, as he travelled up the Rhine as far as Frankfurt on the Yacht Aimée in the summer of 1905. What struck him first was not the romantic river of his imagination but the industrial landscapes of the lower Rhine ("une ville de cheminées, de dômes crachant des flammes et fumées rousses ou bleues ... une fonderie gigantesque, dans laquelle travaillent nuit et jour 24,000 ouvriers. ...Comment vous dire l'impression de ces châteaux de fonte, de ces cathédrales incandescentes, de la merveilleuse symphonie des courroies, des sifflets, des formidables coups de marteau qui vous enveloppe. ...Ce que tout cela est musical! aussi j'ai bien l'intention de m'en servir." (Orenstein  letter 19).
A week later in Frankfurt, it was the beautifully preserved old town and its historic associations which inspired him: "Vu déjà le musée, qui contient un admirable Rembrandt, des Kranach, et surtout un Vélasquez! Quant à la vieille ville, c'est inouï. Tellement bien conservée, qu'elle en semble truquée. Un tas de souvenirs. Les maisons natales de Goethe, de Rothschild et de Luther. La maison où fut signée la paix de 70." (Orenstein  letter 20).
His next recorded visit was in 1926 when he gave a concert in Hamburg (on 28 January) on his tour with Louise Alvar. (Berlingske Tidende [KÝbenhavn], 30 January 1926).
Another tour in early 1932 brought Ravel to Berlin to conduct his recently completed Piano concerto in G with Marguerite Long. (Their arrival was inauspicious as Ravel failed to get off the train at the agreed station, leaving Mme Long alone on the platform and unable to speak a word of German. They were reunited at their hotel, with Ravel by then having lost only his watch and his onward tickets.) Ravel was hoping that Wilhelm Furtwängler would already have rehearsed the Berlin Philharmonic in the new concerto, but Furtwängler had avoided doing so for fear of giving any wrong indications of the composer's ideas. The rehearsal on the day before the concert was dreadful and everyone was despondent. Miraculously everything came together for the performance and reputations were saved. (Long  p.70-71.)
As political relations with Germany darkened during the 1930s, Ravel had particular reason for concern when a claim was made that he was Jewish and that his works should therefore be subject to the embargo on performances of music by Jewish composers. One source of the controversy can be traced to various German reference books of Jewish biography which were published in the 1930s. The Grosse jüdische National-Biographie (ed. by S. Wininger. Cernauti, Tipografia 'Arte', [1925-1936]) was a multi-volume dictionary which included an entry for Ravel (vol.7, p.391-392; published in 1936). Ravel was also cited in a book called Judentum und Musik, mit dem ABC jüdischer und nichtarischer Musikbeflissener, by Hans Brückner and Christa Maria Rock (2.Aufl. München, H. Brückner, 1936). A letter of complaint was sent in Ravel's name to Brückner, who gave the source of his information as the Handbuch der Judenfrage (39.Aufl. Leipzig, Hammer-Verlag, 1935). Brückner agreed to correct the information in future editions of his book (Orenstein  letter 343). The question of performances of Ravel's works was taken up with Joseph Goebbels by the French ambassador to Germany, and the resulting enquiry concluded that there was no boycott of Ravel's music either in concert halls or on the radio (Orenstein  p.575).
Roland-Manuel also provided this reflection on the issue:
"It is also worth noting that the same patronymic [Ravel] belongs to certain Jewish families; in such cases Ravel is derived from "Rabbele" - a young rabbi - which gave rise in America and, recently, in Germany, to a belief in Ravel's semitic origins. Many proofs have been produced in support of this mistaken opinion; especially the interest which Maurice Ravel took in Jewish matters, his harmonization of Hebrew melodies, and, above all, the close friendships he formed with several Jewish people who were - and are - some of his finest interpreters and best friends." (Roland-Manuel  p.14). Roland-Manuel was one of those friends.