The Battle of Grand Gulf was fought on April 29, 1863, during th: Unlike Icelandic and Faroese, which were isolated, the development of English was influenced by a long series of invasions of the British Isles by other peoples and languages, particularly Old Norse and French dialects. These left a profound mark of their own on the language, so that English shows some similarities in vocabulary and grammar with many languages outside its linguistic clades—but it is not mutually intelligible with any of those languages either. Some scholars have argued that English can be considered a mixed language or a creole—a theory called the Middle English creole hypothesis. Although the great influence of these languages on the vocabulary and grammar of Modern English is widely acknowledged, most specialists in language contact do not consider English to be a true mixed language.[21][22]