Beirut, Lebanon - As US Marines spilled from landing craft onto the beach south of Beirut girding themselves for resistance, it was not gunfire that they confronted - but locals waving and cheering them on.

Bikini-clad sunbathers rose eagerly to their feet, villagers arrived on horseback, and workmen downed tools and ran to the sun-beaten shore 10 kilometres from the Lebanese capital.

If the unlikely scene 55 years ago on July 15 marking Washington's military debut in the Middle East during Lebanon's first civil war could have been from a movie, its implications would be far more serious.

"This was the first overt US military intervention in the region," said Maurice Labelle, a visiting history scholar at the University of Saskatchewan.

"It served as evidence that Washington was prepared, willing and able to intervene at its discretion in the Middle East, regardless of local and regional popular opinion. It became much easier for Lebanese and Arab peoples to think and speak of the US in imperial terms."

A Lebanese tank patrols after US 1958 invasion [Pat Bartol]

But on the yellow sands of Khalde beach that day in 1958, the atmosphere was one of excitement as Lebanese boys rushed to the water's edge to help the invaders drag their equipment through the surf.

By noon the following day, about 5,000 "leathernecks" - slang for US Marines - had landed and within four days 14,000 members of the US military had fanned out across Beirut.

Gary Bailey, a young Marine corporal at the time, recalls: "When the call came to lower the landing craft with all the troops, the order of the day was not to fire unless being fired upon. We circled just like we used to see in the movies in World War II and made the wave to hit the beach.

"I know there were a lot of prayers being said in silence because when that ramp went down we didn't know what was going to happen. We landed in the local people's backyard. No one fired on us."

Cold War atmosphere

Operation Bluebat, as it was called, was the first assertion of a pledge in 1957 by President Dwight D Eisenhower at the height of the Cold War to resist Soviet interference in the region.

But the origins of the invasion lay in the growing panic sown by Arab nationalism within the Lebanese government of the Christian Maronite president Camille Chamoun.

The pan-Arabist ideals of Egypt's president, Gamal Abdel Nasser, whose Soviet ties unsettled the West, were engulfing the Middle East, and Lebanon's Sunni Muslims wanted to join the new United Arab Republic formed by Egypt and Syria.

Civil unrest - fuelled by explosive claims that Chamoun aimed to change the constitution to stay in office - spread as an opposition across sectarian divisions clashed with loyalists.

The United States did play an important diplomatic role in fomenting discussions between belligerent adversaries … but, simply put, US troops were not needed in Lebanon, their physical presence only hindered the political situation there. Maurice Labelle, visiting scholar at the University of Saskatchewan

The final straw for the embattled Lebanese leader was a bloody military coup in Iraq on July 14, in which the country's pro-Western king and prime minister were unceremoniously shot dead.

Chamoun fired off an SOS to Eisenhower - and US troops stepped onto the packed Beirut shoreline the very next day.

Yet the lack of opposition they encountered was a revelation for the soldiers.

Ray Hoffbauer, a radio operator, recalled: "We were not told where we were going and also told not to ask. It was only after we were out at sea that we were told we were going to Lebanon.

"We were told the Marines had made a landing, but that there was no combat involved. We were surprised to hear that because everything had been so secret."

Eisenhower's deployment at Khalde was not announced to the Lebanese public until troops had encircled Beirut International Airport three hours later, says Labelle.

"It is likely that those Lebanese at the beach that day perceived the arrival of US troops as another routine R&R stop-over, as Beirut had been at the time a frequent vacation spot for US Marines," the historian says.

"Tourism, after all, was a major source of income for many Lebanese. And US Marines had a reputation of spending money while in Lebanon."

The US forces would encounter little but the occasional pot-shot from rebels.

Pat Bartol, then a private in the airborne division, told Al Jazeera he "was under sniper fire twice but did not get too excited as I was only 19 at the time and felt bulletproof".

As a result, many US servicemen were left to indulge in none-too soldierly activities.

"I remember being sent on a goodwill mission where I and a couple of others were sent to dine with a local family," said Thomas Zmecek, then a 19-year-old corporal in the Marines. "We ate well, drank a lot, were provided with swimming trunks and swam with the family's daughters and had a grand time."

'Overreaction'

It soon became clear Operation Bluebat had been what Labelle brands an "overreaction" - as there were no signs of either a communist or United Arab Republic takeover - and Lebanon's first civil war petered out within months.

By October, US forces were departing with the loss of just one man to hostile fire - two others drowned while swimming.

The installation of a new Lebanese president had ended the conflict, albeit with a death toll of up to 4,000 people.

Labelle said the strife of 1958 is best understood not as a sectarian conflict, but as a battle of political wills - not least a reaction against Chamoun's excesses and pro-Western stance.

Opposition to the controversial president's rule had even included some Christians, among them the Maronite patriarch.

Yet according to Labelle, the US action in Beirut, sandwiched between the more gruelling interventions in Korea and Vietnam, was to prove far more significant than many then imagined.

Washington's self-satisfaction over the campaign and a belief in its overwhelming success were misplaced.

"The United States did play an important diplomatic role in fomenting discussions between belligerent adversaries … but, simply put, US troops were not needed in Lebanon, their physical presence only hindered the political situation there," Labelle said.

Moreover, Operation Bluebat's legacy bolstered a belief that the US had a "special mission in the Middle East to serve as the beacon of democracy", he said.

"In many ways, the flawed US recollection of 1958 served as evidence and manufactured consent towards future military interventions in the region, most notably the second Lebanese civil war of 1975-1990."

Alasdair Soussi is a freelance journalist based in Glasgow, Scotland. Follow him on Twitter: @AlasdairSoussi