Question: when was the Battle for Castle Itter fought that is explained in a book by Stephen Harding?

Context paragraphs:
House at 52 Frost Mill Road: Stephen Harding House, also known as the Wright-Underhill House and Turbillon, is a historic home located at Mill Neck in Nassau County, New York.  The house is believed to date to the 18th century settlement period, then substantially expanded and restyled in the Colonial Revival style in the late-19th and early-20th centuries.  It is a two-story, five bay, frame dwelling with a side gable roof with three dormers.  It has two two-story additions.  Also on the property are the contributing wood-framed shed, horse barn, and chicken coop.

Stephen Harding (cricketer): Stephen Harding (dates of birth and death unknown) was a noted English cricketer of the mid-18th century who played for Chertsey, All-England and Surrey.  Harding was a hard-hitting batsman and a good bowler, although his style and pace is unknown.  He featured in single wicket contests and seems to have been a fine all-rounder.

Stephen Harding House: Stephen Harding House is a historic home located at Sea Cliff in Nassau County, New York.  It was built in 1878, and is a 1 1/2-story, rectangular balloon frame vernacular Queen Anne style cottage.  It has three small one-story additions.  It features a replacement front verandah with turned spindle supports and decorative frieze and railings and fishscale shingles on the gable ends.  The cottage was built during the period when Sea Cliff functioned as a Methodist camp.

Battle for Castle Itter: The Battle for Castle Itter in the Austrian North Tyrol village of Itter was fought on May 5, 1945, in the last days of the European Theater of World War II.

Stephen Harding (disambiguation): Stephen Harding was an English-born monk, abbot and Christian saint.

Church of St. Stephen Harding in Apátistvánfalva: The Church of St. Stephen Harding in Apátistvánfalva or Apátistvánfalvian Church (Hungarian: "Apátistvánfalvai Harding Szent István templom," Slovene: "Cerkev Svetega Štefana v Števanovci" Prekmurje dialect: "Števanovska cerkev Svétoga Števana Hardinga") is a Baroque Roman Catholic Church in the village of Apátistvánfalva (Števanovci), Hungary.  It is near the Hungarian-Slovenian border, in the Vendvidék region.  Its patron saint Stephen Harding was an English saint and the founder of the Cistercian Order.

The Last Battle (Harding): The Last Battle: When U.S. and German Soldiers Joined Forces in the Waning Hours of World War II in Europe is a book by the historian Stephen Harding which tells the story of the World War II Battle for Castle Itter.

Jean Borotra: Jean Laurent Robert Borotra (] , ] ; 13 August 1898 – 17 July 1994) was a French tennis champion.  He was one of the famous "Four Musketeers" from his country who dominated tennis in the late 1920s and early 1930s.  Borotra fought in the battle for Castle Itter in WWII.

Itter Castle: Itter Castle (German: "Schloss Itter" ) is a 19th-century castle in Itter, a village in Tyrol, Austria.  During World War II, it was turned into a Nazi prison for French VIPs and was the site of an extraordinary instance of the U.S. Army, German Wehrmacht, Austrian Resistance, and the prisoners themselves fighting side-by-side against the Waffen SS in the Battle for Castle Itter.

Stephen Harding: Stephen Harding, O.Cist. , (French: "Étienne Harding" , died 28 March 1134) was an English-born monk and abbot, who was one of the founders of the Cistercian Order.  He is honoured as a saint in the Catholic Church.

Supporting paragraphs: The Last Battle (Harding) Battle for Castle Itter
Answer: May 5, 1945