[8] For one month in 1911, he served as United States Ambassador to Costa Rica (having been appointed by President William H. Taft) before his wife's ill health in the country's high altitude forced him to leave the post.

[10] in the British magazine The National Review,[11] in which he warned of a coming war between Germany and Britain, claiming that "unperceived by many Americans, the European balance of power is a political necessity which can alone sanction on the Western Hemisphere the continuance of an economic development unhandicapped by the burden of extensive armaments" and that "if ever decisive results are about to be registered of a nature calculated to upset what has for centuries been the recognized political fabric of Europe, America can remain indifferent thereto only at its own eventual cost.

[14] Einstein blamed the cooperative pact between Germany and the Ottoman Empire as the supportive and responsible agents behind the massacres[15] He also pointed out that the stockpiles of armaments that was used as a justification for the arrests was in fact a "myth".

[16] By August 4, Einstein wrote in a diary entry that the "persecution of Armenians is assuming unprecedented proportions, and is carried out with nauseating thoroughness.

[18] Einstein served as the United States Diplomatic Representative (Chargé d'Affaires), with responsibility for looking after British interests, in Sofia, Bulgaria from October 1915 to June 1916.

[20][21] He also succeeded in "a game of hide and seek" with the authorities to get considerable improvement in the treatment and the condition of British prisoners of war.

[2] On October 8, 1921, Warren Harding appointed Einstein to replace Richard Crane as the United States Envoy Extraordinary and Minister Plenipotentiary to Czechoslovakia.

[6] This report was denied by Lady Waldstein, who indicated that the father's only wish regarding Lewis Einstein was to see that he was "taken care of", a means she accomplished by granting him an annual allowance of $20,000.