When the american settlers signed the texas declaration of independence texas became:

When the American settlers signed the Texas Declaration of Independence, Texas became an independent nation.

This is why Texas is still referred to this day as the "Lonestar Republic," as it was considered its own sovereign nation for almost a decade during the early part of  the 19th century. It would not be until 9 years after Texas became independent that it became part of the United States.

c) troops march forward in close formation against newer, more accurate weapons