The battle lines of the Syrian civil war are edging closer to Krak des Chevaliers, the most famous Crusader castle ever built. The massive walls and towers of the great fortress on its hilltop glistened white in the sunshine yesterday, as the Syrian Army fought rebels in the valleys below.

The rebels hold the castle and the two nearby villages of al-Zara and al-Hosn while much of the rest of this area, 25 miles west of Homs city and just north of the Lebanese border, is inhabited by Christians who support the government. The 13th century castle was damaged by a Syrian air force attack and mortars last year and the Syrian government says it is eager to prevent further damage.

“We launched an operation to retake this area last week,” the governor of Homs, Talal al Barazi, told The Independent. He said that so far the army had taken 50 per cent of al-Zara “and we think the rest of it will be in our hands within a week.” Syrian army officers on the spot were more cautious on how long the fighting was going to last, saying it might be a week or two.

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The reason why the Syrian army is attacking has less to do with Krak des Chevaliers’ strength as a defensive position and more to do with strategic importance of the area in which it stands. This commands the main road between Homs and Tartous on the coast, just as it did in the 13th century when the castle was rebuilt in its present form by the Knights Hospitaller (its original and less romantic name was Crac de l’Ospital).

But Mr Barazi says of more immediate importance is the gas and oil pipelines and electric power lines that run through al-Zara which the rebels can sever at any time. They blew up the Homs-Tartous oil pipeline at al-Zara on 3 January and recently cut the power line leaving Homs city without electricity for 24 hours.

The fighting has led to losses on both sides. Mr Barazi said he had just come back from a hospital in Tal Kalakh, a town just south of Krak, after a day’s fighting in which the army “had lost 10 dead and 27 wounded, while we killed 65 terrorists and captured five of them.” The battle had eased off yesterday, a day of intense cold for Syria which saw part of the country under snow.

A further reason for the army’s push towards Krak and the land around it has to do with the sectarian geography of this part of Syria. The two centres held by the rebels, al Zara-and al-Hosn, the latter just below the castle, are Sunni Muslim and sympathetic to the rebels, but the other villages are Christian and support the Syrian government, often joining the National Defence Force militia.

This part of Syria is much like Lebanon when it comes to sectarian diversity and long-held animosities exacerbated by the civil war.

Syrian army officers said that these worsened recently when two Christians, a man and a women, had a late dinner at a hotel called the Alwadi and were stopped by armed men as they drove home. “As soon as they said they came from a nearby Christian village called Marmarita they were killed,” said an officer. In another sectarian killing a Muslim from al-Hosn village was reportedly killed by Christian militiamen.

These stories of sectarian atrocities by all sides may be exaggerated in the telling, but there is no doubt about the extent to which they produce an atmosphere of hatred. An officer in Tal Kalakh produced a picture on his phone of the severed heads of two men being held by what he says were two young rebels inside al-Zara.

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The army is getting closer to Krak des Chevalliers but will they try to take it? And, given the way in which the Syrian army relies on its artillery and aerial bombing, might it be destroyed?

Mr Barazi says they are conscious of Krak’s historic significance and will do everything to avoid damaging it. But the castle used to hold a garrison of 2,000 men at the height of its power before it was captured by the Mamluk Sultan Baibars in 1271. It could probably give a good account of itself still. On the other hand, the Syrian army strategy has been to blockade places held by the rebels but only to launch ground attacks against those that are strategically important. This is true of the town of al-Zara with its proximity to gas pipelines and electric power lines. Krak might well be spared for the moment but no monument – however famous – is safe in Syria as was shown by the destruction of the medieval market and Ummayad Mosque in Aleppo.

Fighting in Syria has an on-and-off quality because the Syrian army does not have the numbers to sustain heavy losses from ground attacks.

In the battle for Qusayr it was Hezbollah who fought house-to-house and suffered serious casualties. The rebels are fragmented in organisation, lack heavy weapons and are too short of ammunition to launch big offensives. But though the fighting is intermittent, it very seldom stops. On our way back to Homs from Tal Kalakh a tank briefly blocked the road as it took up position and fired a shot from its gun into the al-Wa’ar district of Homs city, whose 400,000 people are Sunni and where government and rebels dispute control.

Army officers based in Tal-Kalakh in charge of the operation were not saying much yesterday. A burly colonel in his command said “the attack is a military secret.” But he did explain the reason for launching it was that “this area is strategically important because it is so close to Lebanon.”

Last June the government and its Lebanese ally, Hezbollah, had one of its few clear cut victories when they captured the rebel town of al-Qusayr a few miles east of Tal-Kalakh.

Watch: The Syrian government has been "deliberately and unlawfully" demolishing thousands of homes and buildings

