ROSSIGNOL Belgium (Reuters) - The bloodiest day for the French Army in World War One - indeed in its entire history - draws no national tributes, no eulogies by dignitaries, few wreaths laid in respect.

The storied campaigns at the Marne and Verdun are seared into French consciousness But the catastrophic Battle of the Frontiers a century ago that cut down 27,000 French soldiers on August 22, 1914, remains largely unknown.

Despite bayonet charges and a refusal to retreat, the men buried in the moss-covered graves in the village of Rossignol and others like it in southern Belgium perished in the rout by the German army have faded from memory in ensuing years.

"Command, topography, tactics, everything" went wrong in the 15-odd battles that summer day on a front stretching from Alsace to western Belgium, said Jean-Michel Steg, author of "The Deadliest Day in the History of France." Many historians consider Rossignol in the Ardennes the battle's epicenter.

"It was a crash course for the French army into 20th century battle tactics," Steg said.

"They had gone in dreaming of Austerlitz and it was a different world. It was one of those days they crashed into reality," he said, referring to a Napoleonic victory marked by dramatic cavalry charges.

Two elite colonial infantry regiments sent north by General Joseph Joffre to drive a wedge in the German army as it pushed south were wiped out at Rossignol, nestled in southeast Belgium not far from the French and Luxembourg borders.

The majority of officers were gunned down by German machine guns as they led their troops in desperate, unwinnable charges.

"They're experienced, they're tested, and yet they're going to be cut to pieces here in the forest. That's why Rossignol is the most striking battle," said Remy Pierlot of Belgian non-profit MERCi, which seeks to maintain the historical memory with tours of battlefields and sites of civilian massacres.

Reasons given for the French defeat are many - the surprise presence of the 4th and 5th German armies a day before Joffre had expected them, a difficult, unfamiliar wooded terrain, dense morning fog and the bright red trousers worn by French soldiers.

More critical, however, was the intransigent credo of the French military that insisted on all-out offensive attacks.

The lack of defensive training and an inflexible command hierarchy meant the French soldiers - taken by surprise while marching through a dense forest ill-suited to offensive charges - were slaughtered by the thousands by the German artillery protected by defensive positions, and ordered not to retreat.

"There was this offensive spirit - we advance. Joffre said 'We have to make it through, no matter the price.' Well, the price was a generation of Frenchmen," said Jean Dauphin, whose museum in nearby Latour is dedicated to the area's war history.

Within the first three hours of fighting, the Rossignol battlefield was already littered with the bodies of two French regiments and yet the charges kept coming, Steg said.

"By the fourth or fifth attempt you probably start running over the corpses of your friends," he said. "It's unbelievable how those guys did it. It was hell. Those guys were very brave."

The French losses that one day alone are the equivalent of half of all U.S. soldiers killed in 16 years of fighting in Vietnam. More comparable, yet still less severe, are the 20,000 British killed on July 1, 1916, during the Battle of the Somme.

The paradox is the British remember, the French do not, said Steg.


CIVILIAN MASSACRES

Strewn throughout southern Belgium are not only French and German cemeteries but memorials to massacred civilians.