To add to this - for a while French was the international lingua franca in Western Europe, especially for international relations + the educated classes. To some extent, this also applied to the United States since we interacted with Europe. This is not true any more and has not been for years, but every now and then you see (usually very dated and formal) style guides saying that French or French-based words are preferred in certain communications.
The biggest vestige of this is diplomatic credentials - those will often be written in French irrespective of whether the host country or ambassador's home country speaks it.