a conflict that has killed at least 140,000 people and forced millions to flee to seek sanctuary in neighbouring countries.
On the third anniversary of the outbreak of violence, many Syrians have little hope of returning home.
Among them is Maira, 20, who faced a tortuous journey crossing the river that divides Syria from Lebanon while pregnant. Gunfire ripped overhead as she forged ahead, holding the hands of her young sons, aged five and six.
"It was my worst day ... worse than all the shooting and attacking in Syria," says Maira. "I was terrified. It was indescribable."
She scrambled out of the water with her boys and hid in a nearby hillside. Her first 30 minutes as a refugee were spent wet and shivering in the dark until her husband found her and took her and their sons to the refugee centre in a former school, which they now call home.
That was more than one year ago. Today, Maira is now one of more than 2.5 million Syrian refugees. With no negotiated end to the war in sight and many Syrian cities and towns flattened and shell-scarred, there seems to be little hope that the country's refugees will be able to return home anytime soon - if ever.
In Lebanon, which has absorbed more refugees than any other country, approximately one million, the Syrians face many challenges. Lebanon's housing stock is exhausted, forcing many refugees to take whatever shelter they can find and afford. With no formal camps in Lebanon, unlike in Turkey and Jordan, Syrians are often forced to rent accommodation.
In a saturated rental market where even car garages cost £120 a month, making rent payments - in addition to food, water, and medicine - is a huge financial strain on refugee families who have lost everything in the war and are now struggling to start over with little or no work available to them.
Sehr, 39, has not spoken to her husband in a year and does not know if he is alive or dead. She left Syria 18 months ago with her three-year-old daughter, Amal, walking from dusk untils sunrise through the mountains to Lebanon. Today, she lives in a makeshift shelter atop a concrete slab on a remote hillside.
"I used to have a big house," Sehr says. "Financially, we were fine. We owned an apple farm and a store. A bomb hit our house. The walls fell first and then the whole house fell. We lost everything. My daughter and I came here with the clothes we were wearing and 500 Syrian pounds [around £2]."
She now does housework to earn a meagre living to support herself and Amal, which means "hope" in Arabic.
When asked why she chose the name for her daughter — who is just a few months older than Syria's civil war - Sehr's eyes fill with tears as she says: "So she can hope for a better life than this."