The Muslims had turned in their weapons to the UN which had promised not to abandon them
http://news.bbc.co.uk/1/hi/world/europe/675945.stm
In the summer of 1995, two years after it was designated a United Nations Safe Area, the Bosnian town of Srebrenica became the scene of the worst massacre in the Bosnian war. This is an account of the critical days leading up to the killings:
6-8 July 1995
Bosnian Serb forces had laid siege to the Srebrenica enclave, where tens of thousands of civilians had taken refuge from earlier Serb offensives in north-eastern Bosnia. They were under the protection of about 600 lightly armed Dutch infantry forces. Fuel was running out and no fresh food had been brought into the enclave since May.
Serb forces began shelling Srebrenica. Bosnian Muslim fighters in the town asked for the return of weapons they had surrendered to the peacekeepers but their request was refused. The Dutch commander called UN Headquarters in Sarajevo asking for "close air support" after shells and rockets landed close to refugee centres and observation posts manned by peacekeepers.
9 July 1995
The Bosnian Serbs stepped up their shelling and thousands of refugees fled to the town from southern camps ahead of advancing Serbs, who attacked Dutch observation posts, taking about 30 soldiers hostage.
Srebrenica facts
Muslim enclave in Serb-held territory
1991 Population
75% Muslim
25% Serb
Declared safe area in April 1993
UN commander Morillon arrived in March 1993 and said: "I will never abandon you"
Bosnian Serb army and paramilitaries massed in April 1995 including:
Drina Wolves
Seselj's Chetniks
Arkan's Tigers
One peacekeeper was fatally wounded when Bosnian Muslims fired on retreating Dutch troops.
10 July 1995
Dutch Commander Colonel Karremans filed a request for UN air support after the Bosnian Serbs shelled Dutch positions. UN Commander General Janvier initially refused, but agreed after another request from the colonel. Serb attacks stopped before the planes arrived and strikes were postponed.
Some 4,000 refugees were in the town by the evening and there was panic on the streets. Large crowds were gathered around the Dutch positions.
The Dutch commander told town leaders that Nato planes would launch massive air attacks against the Serbs if they had not withdrawn from the safe area by 0600 the following morning.
11 July 1995
The Serb forces did not withdraw, but at 0900 Colonel Karremans received word from Sarajevo that his request for close air support had been submitted on the wrong form. At 1030, the re-submitted request reached General Janvier, but Nato planes had to return to base in Italy to refuel after being airborne since 0600.
UN air power was unable to save the safe area
By midday, more than 20,000 refugees - mostly women, children and the infirm - fled to the main Dutch base at Potocari.
At 1430, two Dutch F-16 Fighters dropped two bombs on Serb positions surrounding Srebrenica. The Serbs responded with a threat to kill their Dutch hostages and shell refugees, causing the suspension of further strikes.
The Bosnian Serb commander Ratko Mladic entered Srebrenica two hours later, accompanied by Serb camera crews. In the evening, General Mladic summoned Colonel Karremans to a meeting at which he delivered an ultimatum that the Muslims must hand over their weapons to guarantee their lives.
12 July 1995
Buses arrived to take women and children to Muslim territory, while the Serbs begin separating out all men from age 12 to 77 for "interrogation for suspected war crimes".
Mladic: Offered Muslims freedom if they surrendered arms
It is estimated that 23,000 women and children were deported in the next 30 hours. Hundreds of men were held in trucks and warehouses.
About 15,000 Bosnian Muslim fighters had attempted to escape from Srebrenica overnight and were shelled as they fled through the mountains.
13 July 1995
The first killings of unarmed Muslims took place in a warehouse in the nearby village of Kravica.
Peacekeepers handed over about 5,000 Muslims who had been sheltering at the Dutch base at Potocari. In return, the Bosnian Serbs released 14 Dutch peacekeepers who had been held at the Nova Kasaba base.
16 July 1995
Early reports of massacres emerged as the first survivors of the long march from Srebrenica began to arrive in Muslim-held territory.
Following negotiations between the UN and the Bosnian Serbs, the Dutch were at last permitted to leave Srebrenica, leaving behind weapons, food and medical supplies.
In the five days after Bosnian Serb forces overran Srebrenica, more than 7,000 Muslim men are thought to have been killed.
Many of them arrived in Tuzla armed, and there were actually a few shoot-outs between them because some felt the leadership had given up Srebrenica - which it did.
Naser Oric and the top leadership, around 17 men, had left 3 months before, in April, and they never even bothered coming back. The town was obviously decided to go to Serbs for some time after the "fall".
There is a book, entitled "Srebrenica Survivors in St. Louis: After the Fall", which has quotes from an extended family, living in St. Louis, circa 1999. Some of the "survivors" are men who were in the army (about 3 of them). All of them say they were told by the acting commander to gather in the city (which meant they had to leave their fortified defenses), while he and the UN told the women and children to head for the UN base at Potocari. This, even before the Serbs got to the city and were still on the outskirts. Serbs started forward after the Muslims launched attacks and ambushes, likely for the set purpose to have the Serbs come. The Serbs were surprised at the lack of resistance on the way to the city.
The Muslim army in Srebrenica was claimed to be in the range of 8,000 - 12,000. The Serb army in the area 1,000 - 2,000 - NO WAY the Serbs could have captured that city, with Muslims in a defensive position, much larger, with Iranian arms. The Dutch Srebrenica report said Iranian arms brought to Sarajevo quickly showed up in Srebrenica.