A jury will begin today deciding the fate of a Brooklyn-born Army paratrooper accused of dreaming up a $50 billion fantasy, complete with a make-believe African kingdom, to con investors and political elites, including a U.S. ambassador.

When Brian Sherry left the Army as a private in 1987, he swapped his fatigues for three-piece suits and French cuffs and became the "administrator" of the so-called Badische Trust - a fictitious, 19th- century German investment house claiming exclusive rights over the fantastic riches of the kingdom, the feds' claim.

While the Badische Trust may have given the allure of sophistication, its principles were the same as a "three-card monte trick in Times Square" - get people interested and then steal their money, federal prosecutor Alexander Southwell said.

"It was all an illusion, a fairy tale . . . complete with castles, princes, barons and dukes," he said.

At the center of the fraud was a document purporting to be a "special deed of trust" from the "Kingdom of Mombessa," according to evidence presented at Sherry's trial in Manhattan federal court.

The document claims that "His Majesty King Henri Francois Mazzamba, Sovereign Ruler of the Kingdom of Mombessa, situated in the Republic of the Congo," hereby appoints Badische to serve as trustee over the "great wealth of my Kingdom."

"The Kingdom contains great wealth in the form of such resources as its land, gold, diamonds and other assets within and upon the earth . . . estimated to be in excess of $50 billion [U.S. dollars]."

To keep up appearances at the "House of Badische," members Sherry appointed to the board were told to observe a strict dress code and protocol "in order to exude the desired image in keeping with the traditions, customs, dignity, statute and in the style of the noble banking and financial houses of Europe."

French-cuff shirts with "tasteful cuff links" were in; "moccasin- style shoes" were out, according to the written dress code.

A gold pocket watch was to accompany three-piece suits, while a "fedora, derby or homburg gentlemen's hat with gloves" was strictly required when wearing a top coat, the policy said.

Pens had to be a "class writing instrument, such as Mont Blanc, etc.," and leather attach cases of elegant design were preferred - "plastic, vinyl cases" were strictly taboo.

Sherry, 41, of Manhattan, who was a decorated soldier based at Fort Bragg, N.C., and Fort Benning, Ga., is charged with helping to create the elaborate illusion to defraud investors out of more than $2 million by promising to provide them with loans of up to $500 million.

His half-brother, Christopher Berwick, 34, of Mount Vernon, in Westchester County, and Cesar Viana, 44, of San Francisco, are also on trial for allegedly taking part in the swindle, in which investors paid "advance fees" with the promise of being able to tap into Badische's fabulous wealth.

But defense lawyer Joseph Bondy told the jury yesterday there was no evidence to suggest Sherry had "anything other than a perfect intent" to finance the loans promised to investors.

He said investors admitted they had failed to meet conditions essential to the loans being paid.

But little did investors know that the House of Badische was actually born as an incorporated company in Delaware in 1997 after Sherry met 77-year-old Manhattan resident, Robert Khimchiachvili.

Khimchiachvili - who also has been charged but is on the run - claimed to be a grand master in the Knights of Malta and curried favor with the ex-Army private first class by making him a "knight," court papers say. The pair initially used their fanciful schemes to convince a group of semi-retired men, including a retired South African ambassador to the U.S., Jim Stewart, to join the board to create a veneer of credibility to investors, jurors were told.

Investors who fell for the ruse, according to testimony, included a New Jersey real-estate developer, Vincent Firth, and Californian telecommunications entrepreneur John Kearns.

They were lured to meetings held in swank hotels such as the Waldorf-Astoria in Midtown, the Hotel Des Bergues in Geneva and the Schlosshotel in Kronberg, Germany.

Professionals from well-regarded firms, such as Merrill Lynch and PriceWaterhouse, were also tricked into attending the meetings.