Evidence of constructing stone and masonry bridges dates back two-and-a-half millennia. In 500 BCE, a Chinese engineer constructed a single-arch masonry and stone bridge of 37 metres that still stands. The remains of Roman aqueducts are proof that their engineers were skilled at constructing large bridges. In the Middle East one of the oldest surviving bridge is the Shahrestan in Isfahan, Iran which has 13 large and 8 small arches and whose foundations date back to the Sasanian era (3rd to 7th century C.E.). Delhi has the remains of a number of arched bridges that were constructed from the reign of Alauddin Khilji (1296-1316) onwards. However, one of the best examples of masonry bridges in the Subcontinent is the Shahi bridge with 10 arches over River Gomti in Jaunpur, UP, that was constructed in the 16th century during the reign of Mughal Emperor Akbar and is still safe for pedestrians.
The science of engineering military bridges also dates back two-and-a-half millennia. In 480 BCE, the Phoenicians constructed a pontoon bridge for the Persian Army to cross over the Dardanelles. In his Anabasis, the Greek historian Arrian credits Alexander with constructing a bridge of boats across the Indus and believed that the skeleton framework was of huge wicker baskets. However other historians state that it was constructed of boats which were subsequently cut into smaller sections and transported to the River Jhelum.
Roman engineers were also skilled at crossing large waterways and during the Gallic War of 55-53 BCE, they constructed wooden beam bridges across the Rhine for the army of Julius Ceaser.
Armies on the march in Northern India crossed rivers either by ferry, fords or boat bridges. The last two options were possible only in the dry months when the rivers generally shrank to one-third of their size and volume, and that is why it was feasible to campaign during these months. Alexander forded the Indus at Hund in the winter months and fought Porus on the banks of the Jhelum in May. However, as he penetrated further into the land of five major rivers during the monsoons, his army nearly rebelled.
All 17 of Mahmud of Ghazni’s campaigns in India were during winter and Emperor Babur crossed into India in early 1526 and fought the First Battle of Panipat in April that year. The Second Battle of Panipat was fought in November 1556 and the third between Ahmed Shah Durrani and the Marattha Empire was fought in January 1761. Like Mahmud of Ghazni, all nine of Durrani’s campaigns into the Punjab were during the dry season from September/October till May/June.
Over the centuries many armies crossed the Indus from fords, of which the most well-known was the one at Hund
After Alexander’s boat bridge at Attock, the next recorded evidence that I found of a boat bridge over the Indus is during Timur’s invasion of India in 1398. He crossed the river east of Bannu over a bridge built of boats and three-legged trestles that was constructed in two days. However, another source states that the bridge was made of rafts and bundles of reeds. The most famous of the crossings over the Indus with a boat bridge was at Khairabad (more popularly known as Attock after the fort) and became a permanent feature during the rule of the Mughal Emperors. In fact, the Mughal rulers went to extreme lengths to ensure that communication was uninterrupted as far as possible over all the rivers of the Punjab. In September 1652 heavy rains in the entire Indus plain flooded all the rivers and streams. A bridge of 40 boats was constructed at Jalala on the Indus, while 55, 56 and 50 boats were used to bridge the Jhelum, Chenab and Ravi respectively. Further down the province, a bridge of 104 boats was erected at Buh over the combined waters of the Beas and Sutlej.
Maharaja Ranjit Singh also periodically constructed a boat bridge over the Indus when the territory came under his control. A report by a British Engineer officer who crossed the Indus in 1839 provides a detailed description of the Bridge of Boats at Attock. The boats were owned by the Mallees who were brought to this site by Emperor Akbar 300 years before. The bridge could be constructed at two locations. Upstream it required 34 boats and was open till May but the one downstream could remain open till June because it was confined between steep banks and required between 17- 20 boats depending on the width of the channel. The bridge was assembled by a crew of 40-50 in 15 days but in an emergency it could be assembled in five days. The planks which made the road-way of the bridge were covered with mud and straw and the anchors were of wooden framework filled with stones, each weighing 1.5 tons.
The Sikh government had it built annually after the rainy season, around the 20th of October. When the bridge was operating, the Mallees were paid 4 annas (1/4 Rupee) a day per boat by Ranjit Singh’s government and they also earned by a toll of 4 annas for laden bullock carts and less for livestock and people. Camels could cross but elephants were not allowed over the bridge. Four of these boats were used to ply a ferry between Khairabad and Attock and when the river was running high, each required a crew of 35-40. Each ferry could transport 250 infantry or 50 soldiers and 12 horses.
The same British officer records that the Indus could only be forded between Attock and Tarbela at five places but another mentions nine. Of the five fords, the two closest to Attock were manageable only in the month of January. And in one of them, which had only two channels, the water was breast high. Eighteen kilometres upstream was the third and only ford which was available throughout the year except from May till October when rain and snow melt swelled the river.
Over the centuries many armies crossed the Indus from these fords, of which the most well-known was the one at Hund. In more recent times, the Indus was forced by Ranjit Singh in the spring of 1823 but with near disastrous consequences. He had earlier sent an army to evict the Afghans from Peshawar, but when the Afghans demolished the bridge at Attock, the Sikh army was trapped near Nowshera. Desperate to relieve this force and rescue his son who was in command, Ranjit Singh brought up his army opposite Hund. On the opposite bank, a lashkar of thousands of fighters led by Syed Ahmad Shah of Buner had started forming. Fortunately, the spring rains had been delayed and though under fierce attacks, Ranjit Singh forded the Indus at night. The guns were transported across on the back of the elephants and the soldiers joined hands and crossed with their accoutrements on their heads. However, he lost close to 7,000 men in effecting a passage.