Imperial Schrade was an American knife company. Most of their products were made in the US. Some were produced overseas, including the SAK-style knives which were made in Germany, reportedly by Adler (the comparison above seems to confirm this). The original company is now out of business. The brand name is now owned by Taylor Brands, which also owns a number of other knife brands, and all current production is done outside the US.
Thanks for checking on the Helle - Adler connection.