The Arrival is the name given to the series of encounters between appearing Colonials and the world's Great Powers (referred to collectively as the 'Thirteenth Tribe'). At first these were sightings of strange aircraft and airships, flying objects too large and of a type not in service with any country in the world and appearing all across the world concurrently. A high proximity of 'arrivals' were in the western hemisphere.
The most friendly of encounters between parties were considered curious at best, with large crowds typically coming out to watch a 'UFO' travel overhead. Typically though they were stand-offish meetings between the Colonials and the scrambling military of a Great Power. For example; near London anti-aircraft artillery fired on an appearing Colonial 'airliner', while off Florida a Naval Flight intercepted and attempted to shoot down a Viper wingpair. A Colonial military airship dropped bombs in Ruhr before making its way towards the Atlantic and Colonial troops landed in Texas in large enough numbers and with significant enough firepower to secure themselves and begin expelling or harassing locals while in search of supplies.
Though violence was sporadic and unplanned, and as such were not sustained- tensions increased rapidly and the opportunity for peaceful meetings reduced while the disoriented Colonials took it as their first priority to assemble and secure themselves. Deal with locals second. The disorder that the Colonials appeared in also led to different ships claiming to speak for the movement and complicated diplomacy. The Arrival itself is considered to have lasted just over a month and a half.
Directly involved parties in encounters leading to violence or losses included Germany, Spain, Britain, France, Mexico and United States with sightings across numerous other countries and territories generally not turning into 'combats'. Losses are believed to have included twenty three people over London and a Colonial 'airliner', a Viper over Alsace and two more Vipers, four Navy fighters in the Gulf of Mexico. Colonials chose to congregate over America where a military presence had landed and quickly established itself unilaterally in what it thought an underpopulated area. The lack of a coordinated voice for the Colonials meant that the drift towards America was met with suspicion and led the US to move planes, tanks and troops against them... in the first few days of the 'Arrival' proper a Colonial Ambassador took to the airwaves with an explanation from where the Colonials had come, and how and why. Disbelief and skepticism was widespread among the people of world by the end of the 'Arrival' while the US Army was engaged in a stand-off with landed Colonials.