Freeing slaves during the civil war led to it. As Sherman was marching to the sea, he freed numerous slaves who now became refugees and joined him in the march. He made the special order because they had to be somewhere since they didn't have any land or property.
"Not only does it allow for more skilled and qualified workers to assist with the employment needs of businesses and thereby support the economic growth of the country, immigration in Canada also reunites families and supports refugees in establishing a new life."
He made many contributions to physics and chemistry, especially in the fields of discovering electrolysis & diamagnetism.
