In the mid 1800s, the specific network of route and safe house use by people ecaping slavery was know as

underground railroad

Explanation:

The Underground Railroad.

Explanation:

It was well-known -- well, as well known as it can be since it's was sort of a secret -- throughout the African-American slaves in the 19th century. The Underground Railroad was used as a means to escape from slavery in the South into free states and Canada.

explanation: idk

first, the romans stayed isolated because they had to defend their own territories from neighboring cities that were harassing them, like the etruscans. second, once the romans managed to defeat their neighbors, and started to expand their territory, they started to build roads and bridges. finally, now that the romans have covered their territory with roads functioning as highways, they could mobilize their legions faster to assemble larger military units in a specific place.