The 101st Heavy Anti-Aircraft Regiment, Royal Artillery (101st HAA Rgt) was an air defence unit of Britain's Territorial Army raised in northern Scotland just before World War II. After defending the naval base of Scapa Flow against air attack in the early part of the war, the regiment went to India and later took part in the Burma Campaign in the anti-aircraft role and with heavy howitzers in support of ground forces, even on occasion fighting as infantry. It was reformed in the post-war TA (as 501st HAA Rgt) and continued until the abolition of Anti-Aircraft Command in 1955.