Toronto. On the eve of the Great War, the son and namesake of Ernst Leitz, Ernst Leitz II, arrived in the Big Apple with the novel tiny ur-Leica created by Oskar Barnack. Leitz took a number of street scenes with the tiny camera to the indifference of New Yorkers since cameras of the day tended to be much larger, tripod mounted, or box shaped.
One photograph has survived and is frequently reproduced, showing that work on the tiny camera began over a decade before it was marketed. The Great war intervened delaying its release until a market turn-down for microscopes prompted its manufacture and sale in 1924.
Information abounds on the Leica and its place in history such as wikipedia’s “Leica_Camera“, the brief history on the site “Not Quite in Focus“, and Wild-Heerbrugg’s excellent “history and milestones of Leica” (Wild-Heerbrugg also made microscopes and once collaborated and merged with Leitz. The Canadian branch was called Wild-Leitz when I first visited in the late 1970s/early80s ). Many more sites show up on a Google browse.