The Only Use of

fortify
in
Anne Frank, the Diary of a Young Girl - Definitive Edition

Just for a change (since we haven't had one of these in so long) I'll recount a little discussion between Mr. and Mrs. van D. last night: Mrs. van D.: "The Germans have had plenty of time to fortify the Atlantic Wall, and they'll certainly do everything within their power to hold back the British.†
p. 320.4

Definition:

to make stronger

in various senses, including:

to add defensive fortifications to a site to withstand attack -- as in "fortify the camp"
to make a structure or organization stronger -- as in "fortify the wall"
to inspire emotional and mental strength -- as in "fortify her spirits"
to strengthen an argument -- as in "fortify our argument"
to add nutrients to increase the healthfulness -- as in "bread fortified with folic acid and iron"
to add alcohol to make a drink stronger and/or less prone to spoiling -- as in "port, sherry, madeira, and other fortified wines"