I desire to direct your attention to the fact that citizens of the United States, or persons claiming to be citizens of the United States, are large holders in foreign lands of this species of property, forbidden by the fundamental law of their alleged country. I recommend to Congress to provide by stringent legislation a suitable remedy against the holding, owning or dealing in slaves, or being interested in slave property, in foreign lands, either as owners, hirers, or mortgagors, by citizens of the United States.

Third State of the Union Address (1871)