He was born to the Baltic German noble von Wahl[a] family in the then Russian Empire and spent most of his childhood in Tallinn (Reval) and the capital Saint Petersburg.

He was first introduced to Volapük by his father's colleague Waldemar Rosenberger and even started to compose a lexicon of marine terminology for the language, before turning to Esperanto in 1888.

After the failure of Reformed Esperanto in 1894, of which Wahl had been a proponent, he started work to find an ideal form of an international language.

Wahl developed the language over several decades on the advice of its speakers, but became isolated from the movement (then centred in Switzerland) from 1939 after the start of World War II.

While at university, Wahl joined the Baltic German Nevania corporation [et] operating in St. Petersburg, where he served as treasurer in the autumn term of 1891.

Full of stories from Cooper, Gustave Aimard etc, I played American Indians with my friends, and conceived the idea of a special quasi-Indian jargon for our games.

He must have considered this time sacred, because decades later, for example, at my sister's wedding, he appeared in a tsarist uniform.It is, however, unlikely that Wahl participated in the suppression of the Sveaborg rebellion, having already been released from service by then.

[11] Wahl's teaching style was described in the memoirs of the later Estonian Minister of Education Aleksander Veiderma, who himself studied at St Peter's High School of Science from 1906 to 1909: Matemaatikat ja füüsikat õpetas veel Edgar von Wahl, endine mereväeohvitser, kellel oli alati varuks tabav märkus mõne sündmuse või isiku kohta.

Ta oli kaunis räpakas füüsikakatsete korraldamisel: sageli murdusid riistad või purunesid klaasid.

Mathematics and physics were also taught by Edgar von Wahl, a former naval officer who always had some catchy remarks about an event or person.

At the turn of the century, Wahl began to publish articles on linguistics in specialized publications, as well as writing in various Tallinn newspapers and magazines.

[27] In February 1918, at the time of the Estonian Declaration of Independence, Wahl expressed a desire to join the voluntary militia Omakaitse.

He represented the idealistic pan-European idea and did not like the National Socialist government of Germany, calling it a "termite state".

This guy is crazy!In the first year of Soviet rule in Estonia (1940-1941) Wahl managed to escape any repressions, although some of his relatives were arrested.

Wahl was arrested on 12 August 1943, because of letters sent to Posen, to his wife's sister-in-law, that were caught by the censors in Königsberg in July of that year.

Therefore I want to warn you and everyone else in the same situation and ask you to leave Wartegau if possible, or at least any means of escape when the Arab uprising breaks out.

During the interrogation Wahl did not deny what he had written, and repeated several of the accusations he had made, "firmly believing" in the veracity of his predictions.

He was held for some time in the Tallinn "labour and education camp", but the testimony given during his interrogation was considered strange by the Sicherheitsdienst, and so Wahl was sent to be examined at the Seewald mental hospital [et].

[36][40] During the bombing raid in March 1944, Wahl's house, including his archive collection, was destroyed, which came as a great shock to him.

Three years later, in a letter to the Finnish Occidentalist Armas Ramstedt, he recalled that what had happened was a real disaster, during which many irreplaceable and unique materials were lost.

[41][42] During and after the world war, his foreign colleagues had very little information about Wahl's condition and whereabouts; only in the spring of 1946 was Armas Ramstedt able to restore contact with him.

[43] It is unclear why the hospital staff at Seewald enabled such correspondence; perhaps that they may have recognized his dedication to linguistics when being supportive to his communication with the outside world.

[49] Wahl was also one of the founders of Espero, Russia's first Esperanto society founded in Saint Petersburg in 1891, and became a correspondent for the magazine La Esperantisto.

With the revolutionary events of 1917 and the departure of its members from Saint Petersburg, the association's activities faded away, ending entirely in 1921, but picking up again in Tallinn in the same year.

From 1923 to 1928, he also promoted the language in the serial Occidental, unic natural, vermen neutral e max facil e comprensibil lingue por International relations.

In order to find a suitable language, it was recommended that a competition be held and that the candidates be evaluated by a committee of experts convened by the League of Nations.

[35][61] During these times he was in active discussions with the Danish linguist and author of another planned language Novial Otto Jespersen which culminated in their meeting and the publication of its results as a separate book.

Unlike Esperanto, which became a popular language among labour movements, Occidental speakers in the interwar period were predominantly Western European intellectuals.

Ric Berger, a leading Occidentalist from Switzerland, cited reports from the Eastern Bloc that the name Occidental was a hindrance to promoting the language.

Guido spent a short vacation in Tallinn during the German occupation of Estonia during World War I, but at the end of 1918 he disappeared.