Chiwy, the daughter of a Belgian veterinarian from Bastogne and his Congolese wife, was born in 1921 in the Belgian Congo. She returned to Belgium at the age of nine. In 1940, aged 19, she went to Leuven to be trained as a nurse.
On 16 December 1944, the day the Germans launched their offensive, Chiwy returned to her family in Bastogne for Christmas. At that time the town seemed safely in American hands, but within days was surrounded by German troops advancing into Belgium during the Battle of the Bulge. Chiwy attended to civilian and military casualties with her uncle, a doctor, until 21 December, when she volunteered to serve as a nurse at the first-aid station of the 20th Armored Infantry Battalion, 10th Armored Division, commanded by Dr. John Prior. Chiwy worked at the aid station in the Rue Neufchateau, and even donned an Army uniform in order to go out into the field to collect the wounded while under fire.
On 24 December 1944, the first aid station was hit by a German bomb, killing over 30 wounded men and another volunteer nurse Renee Lemaire. Chiwy was with Prior in an adjoining building and was blown through a wall, but survived unhurt. She continued to assist the American forces until the siege was finally lifted two days later.
After the war Chiwy worked at a hospital treating spinal injuries, married a Belgian soldier and had two children.
She rarely spoke of her experiences after the war, and it was assumed in some historical accounts of the battle that she had died there. British historian Martin King, while researching his book Voices of the Bulge, finally tracked her down in a retirement home near Brussels, hearing her story, and bringing her to public attention.
Stephen Ambrose makes a passing reference to her in his book Band of Brothers, under the name "Anna", and she also briefly appears in the television series based on the book, portrayed by Rebecca Okot.
In July 2015 a documentary film about Chiwy entitled Searching for Augusta: The Forgotten Angel of Bastogne, produced by Martin King and directed by Mike Edwards, won the Emmy Award for Historical Documentary.
Chiwy died on 23 August 2015 near Brussels, Belgium.
On 24 June 2011, Chiwy was made a Knight in the Order of the Crown. The medal was presented in the name of King Albert II of Belgium by Belgium's Minister of Defence Pieter De Crem. On 12 December 2011, Chiwy was awarded the Civilian Award for Humanitarian Service by the United States Department of the Army. It was presented to her by the U.S. Ambassador to Belgium Howard Gutman. On 21 March 2014, Augusta was recognized by her hometown as a Bastogne Citizen of Honor.