In 1925, however, Druze tribes in the south of Syria that were growing frustrated with French colonial rule made a push for independence in what is now known as the Great Syrian, or Great Druze, Revolt. The tribes viewed the convoys as an extension of the colonisers and targeted several of those passing through. In August and September 1925, several drivers and one passenger were injured in raids and over £9,000 in gold was stolen (approximately 477,435 pounds sterling today).

The Nairn Transport Company had to change its route. For six months, it operated on a route that was 322 kilometres longer: Its drivers would bypass Damascus and instead travel to Baghdad through Jerusalem, Amman and Rutbeh.

Their path changed again when in 1926 the French authorities provided armed cover for a new route running through Tripoli, Homs and Palmyra before tackling the Syrian Desert to Baghdad. It wasn’t until the revolt was crushed and its leaders executed, that the Haifa-Beirut-Damascus-Baghdad route was reinstated.

The Amman-Rutbeh route, however, proved fruitful: due to the extreme conditions encountered on the roads between Amman and Rutbeh, the Nairn brothers collaborated with the American Firestone Tire and Rubber Company to develop a longer-lasting tyre made with a synthetic alternative to cotton.

In spite of the problems faced in terms of regional instability, extreme road conditions and raiders, prospects for the company remained extremely bright.

On 13 December, 1927, Commercial Motor Magazine wrote that "the Nairn Co. has a good future before it, for there is a steady and considerable traffic of passengers and mails" with "present traffic [amounting] to about 1,800 passengers per year, calling for one journey weekly in each direction." In the following years, business continued as usual, with the company expanding and purchasing a sleeper coach to transport passengers.

By 1936, the company began unofficially offering services to the Iraq Petroleum Company: The Nairn Company would transport hundreds of workers and technicians across the desert to oil pumping sites in the region and along the diverging pipelines to Tripoli and Haifa. This was to be the last prosperous period for the Nairn Transport Company.

In 1937, the company finally fashioned the vehicle that would come to represent it: the Pullman. Beyond the development of longer-lasting tyres, the Nairn brothers also experimented with different types of buses. At first, they used Cadillacs with large radiators they said could withstand "great punishment," but as time went by they transitioned to Safeway buses, six-wheelers and then 18-wheelers with two passenger levels.

The Pullman bus was a luxury bus that could carry 18-passengers in an air-conditioned cabin with a refreshment facility. The Pullman was designed by the brothers themselves, and assembled at their workshop headquarters in Damascus. It was built using different components from various companies. During World War II, many Pullmans were converted for military use. Today, many of Syria’s bus stations, from Hama to Damascus, still bear the name of this vehicle.

World War II saw extremely lean times, though the company trudged forward. In 1941, the Milwaukee Journal reported that the Nairns attempted to keep the Damascus-Baghdad route alive, and succeeded for three months into the war. After the war was over, there was hope that business would be restored. However, due to the creation of Israel, subsequent political upheavals and the advancement of air travel, the Nairns were forced to begin downsizing.

A version of the route existed between Beirut and Baghdad, stopping in Damascus, until 1956, when the Iraqi government imposed a customs tax so steep that the firm was forced to cancel the Damascus-Baghdad route. Eventually, the buses fell into disrepair and in the 1970s the last bus that operated under the name of the Nairn Transport Company and ran between Beirut and Damascus disappeared, thus closing this particular chapter in history.

The impact that the Nairn Transport Company had on the region is undeniable: they paved the way for motor transport across the Syrian Desert and the Jordan Valley. Though the mail they transported was mostly diplomatic and served the foreign legions stationed in the Middle East, their routes were used by copy-cat bus services and eventually aided in the creation of motorways across the desert. Zvi Richter, a British Zionist with a vested interest in the colonial development of Palestine and the Middle East, remarked in a letter to his brother in 1943 that it was "a testament to the vision of the British imperial planners" that a journey that would originally take 30 days to complete had been reduced to approximately 20 hours.

But the routes did more than that: They made it easier for people to journey across four cities to visit family and friends, or simply explore. One Lebanese newspaper in 1924 wrote that the transport company had done more to unite Syria and Iraq than any politicians or ideology had been able to in a decade. And it was true: Many people were brought together on this route. Fuad Rayess, writing in Saudi Aramco World, recalled a conversation he had with another passenger on one of the last trips to Baghdad:

"'You know,’ he said, ‘I thought this trip was going to be very boring, but it has actually been, well, romantic.’ I stared at him in disbelief. Had he lost his senses? Was he teasing me? ‘I mean, look around,’ he said. ‘There's a little six-year-old girl who crooned to a doll in the middle of the desert so it would go to sleep. There's a teacher who thinks nothing of giving an English lesson at 40 miles an hour. There's a driver who used to be a Bedouin. One man is trying to get some valuable clothes through customs and a complete stranger is trying to show him how. And a Frenchman, off alone in Iraq without knowing a word of Arabic; an Iranian professor on his way back from Europe; a young girl mourning a brother who is somewhere at sea on the greatest adventure of his life; and a mother looking for a daughter who may be somewhere in Baghdad right now wondering if she'll ever see her again.’ He shook his head. ‘So many interesting people on one small bus.’"

Zouka Khanoum, an elderly resident of Beirut, echoed these words: "I never personally went… but my husband, may he rest in peace, had frequent trips to Baghdad. After every trip, he would come back with stories of those he’d met, and tell me about what wonderful and different people travelled by bus. He would say they were mostly ajaneb – foreigners – though."

Beyond all this, the bus route stoked the imaginations of all: Omar, a middle-aged man who grew up in Damascus towards the end of the Nairn era, recalls seeing the buses at their depot in Damascus. "As a child, I would grow so excited to see the buses, because in my mind, they represented this out-dated vision of what our countries could have been… I would see the buses frequently, but one day they just weren’t on the streets anymore."

Watching the dissolution of borders and the formation of new ones in a region increasingly identified by its tragedies instead of its literature, architecture and beauty, it is hard to imagine that such a world was once possible, a world where anyone could take a bus from Haifa to Beirut, from Damascus to Baghdad. Remembering this, perhaps, can remind us that another world was within our reach not so very long ago.