Entrench
verb
To dig or excavate a trench; to trench.
To surround or provide with a trench, especially for defense; to dig in.
“The army entrenched its camp, or entrenched itself.”
To establish a substantial position in business, politics, etc.
“Senator Cornpone was able to entrench by spending millions on each campaign.”
Synonyms: trench, consolidate, dig in