In 1942, the United States was one of several countries involved in World War II when the Race's Conquest Fleet invaded Earth. In short order, it became one of the critical Big Five powers who were able to successfully fend off the Race, and by the Peace of Cairo in 1944, was one of the three powers to maintain diplomatic relations with the Race.
By the fourth decade of the 21st Century, thanks to a combination of cultural factors unique to the country and simple luck, the United States stood on the brink of surpassing the Race in terms of technological advancement.
On December 7, 1941, Japanese forces attacked the United States base at Pearl Harbor, Hawaii, drawing the US into World War II on the side of the Allies. Less than six months later, the Race's Conquest Fleet invaded Earth, and that war was abandoned as every human nation was thrown into a fight for its survival.
The US military fared badly in the first year of the war, with Race forces taking pockets of territory throughout the Midwest and destroying Washington, DC with an explosive-metal bomb. In the winter of 1942-3, however, US generals George Patton and Omar Bradley, taking advantage of the Race's low tolerance for cold temperatures, launched a counterattack during a snowstorm that prevented the Race from taking the city of Chicago.
The US became a participant in the Big Five cobelligerency along with Germany, Japan, Britain and the Soviet Union. It benefited from technology exchanges among the group, and received a sample of radioactive plutonium from the Polish Jew Mordechai Anielewicz.
The US atomic bomb program completed a weapon in late 1943 and destroyed the city of Chicago, which the Race was on the verge of taking. It also destroyed the Race-held city of Miami. The Race retaliated by destroying Seattle and Pearl Harbor; Vice President Henry Wallace was killed in the former.
President Franklin D. Roosevelt died in 1944 and was succeeded by Secretary of State Cordell Hull. It was Hull who accepted the Race's invitation to be part of the Peace of Cairo and sent the new Secretary of State, General George Marshall, to represent US interests at the conference. Along with its Big Five cobelligerents, the US was among the first political entity to force an authority of the Ssumaz dynasty to treat with it on equal terms in more than fifty thousand years.
Peace prevailed on Earth, however unsteadily, and the US, like Germany and the Soviet Union (and Japan and Britain to a much lesser extent) took advantage of this peace to build up its technological arsenal. The US built nuclear missile, computers, created its own Internet, and became a space-faring government: It maintained a space station in Earth orbit, flew regular orbital flights, and visited the Moon and Mars.
In 1962 the Race's Colonization Fleet arrived in Earth orbit. It was attacked by the nuclear missiles of an unknown party, and twelve of its starships were destroyed. The attack had been ordered by none other than US President Earl Warren, but this would not come to light until 1965.
In 1963 the US completed the Lewis and Clark, a space vessel which it sent to the asteroid belt. This was the first spaceship of human build to use an atomic engine and was considered a forerunner of a starship with interstellar capability.
The US allowed the Race to set up shrines to the Spirits of Emperors Past within its territory, making it unique among the human powers. The US believed it could not bar the shrines under the Free Exercise clause of its Constitution. The Race's cult of emperor-worship was adopted by some Americans, mainly Californians.
The US remained neutral in the Race-German War of 1965, but Warren took note of the destruction to which Germany was subjected. U.S. offers to broker a peace were rejected, and the resulting agreement was reached with the aid of the Soviets instead.
In 1965, Straha, an exiled Conquest Fleet shiplord who had defected to the US in 1944, brought incriminating evidence of US involvement in the Colonization Fleet episode provided to him by his friend, Sam Yeager, to the attention of Fleetlord Atvar. Atvar presented the US with three choices: allow the Race to destroy an American city; discontinue its space program; or go to war. Warren knew that, even with Soviet help, the US could not win a war, and also knew that the dismantling of the space program would be an unacceptable setback. Warren therefore allowed the Race to destroy Indianapolis, then committed suicide and was succeeded by his Vice President, Harold Stassen.
As ginger use became widespread among the Colonization Fleet's females, causing them to become sexually receptive all the time, many who frequently mated with male friends became interested in entering into exclusive mating arrangements, or marriages. As the Race considered monogamy the height of perversion, these couples were not welcome in their own government's territory. The United States accepted many monogamous Lizards as defectors, thus deepening their own talent pool and simultaneously depleting the Race's.
In the late 1970s the US began experimenting with cold sleep technology. A number of people it considered useful (and, not coincidentally, troublesome) such as Sam Yeager and Glen Johnson were put into suspended animation in preparation for an interstellar journey to Home at sublight speeds. The US launched its starship, the Admiral Peary, in 1997. It arrived in Home orbit in 2031, the first starship not of Race manufacture to visit Home in that planet's history.
The Admiral Peary was sent with the primary mission of establishing an embassy on Home. It had originally intended for Dr. Henry Kissinger to be diplomatic chief of mission, but he failed to awaken from cold sleep and Sam Yeager became ambassador.
Yeager and his team dealt primarily with Atvar, Race psychologist Ttomalss, and Tosevite citizen of the Empire Kassquit. Yeager was also granted an audience with the 37th Emperor Risson, making him the first ambassador to be received by a Ssumaz emperor since the unification of Home.
Despite a willingness to negotiate in good faith by both parties, the Race could not accept the threat presented to it by the US's presence in the Tau Ceti system. The tone of the negotiations steadily deteriorated over a period of several months, and war seemed increasingly likely. Then the FTL ship Commodore Perry arrived in Home orbit, a clear sign that the United States had surpassed the slow-moving Race technologically--thus giving the US the very real option of destroying the Race's entire empire if the Race attempted to destroy the United States and Earth. Under an unprecedented threat, the Race sought to reach a peaceful understanding with the US.