Families of UK troops killed in Iraq have been told they cannot challenge the government's refusal to have an inquiry on the decision to go to war.
Fusilier Gentle was killed in June 2004
A judge at the High Court ruled they did not have an arguable case that should go before a full hearing.
Ninety-eight British soldiers have died in the war, 75 in hostile action.
The families of six wanted the prime minister "to be held accountable" in public if there was no legal basis for the conflict and its aftermath.
The case was brought by Rose Gentle, whose son Gordon, 19, was killed by a roadside bomb in Basra on 28 June last year.
She was supported by the Stop The War coalition.
In court it was argued the government's decision to go to war was a breach of Article 2 of the European Convention on Human Rights.
In court on Tuesday, Mr Justice Collins ruled there was no case to answer and refused permission for a full hearing.
In a statement, Mrs Gentle said she was "disappointed" at the outcome and that the families still believed the decision to invade Iraq was based on "lies and deceit".
"All I want is for the prime minister to tell the truth about the war," she said.
Peter Brierley, whose son Lance-Corporal Shaun Brierley was killed in a road accident in Iraq in March 2003 said: "I had always believed that weapons of mass destruction would be found in Iraq.
"I could not believe anyone, particularly our Government, would put anyone's lives at risk for a lie."
Lindsey German, of Stop The War, said afterwards: "We are very disappointed with this decision.
"We obviously haven't heard the judge's reasons but we feel it is overwhelmingly in the public interest for a full inquiry to be heard."
She added: "We think this is a disservice to the dead soldiers, their families and the people of Britain overall, who really should expect better from the government in the matter of taking them into illegal and unnecessary wars."
Andrew Burgin, of Military Families Against the War, echoed her disappointment.
He said: "We had hoped that the decision would go in our favour, particularly as we believe that the families have a very good case for a full public inquiry into the war.
"Demands for such an inquiry are building up, both inside Parliament and outside, and we shall be continuing our campaign by other means."
The six soldiers died in roadside bombs, a road accident, a helicopter collision and under friendly fire.
Their lawyer, Rabinder Singh QC, had argued Article 2 of the convention obliged the State to conduct a proper, adequate investigation when lives were lost.
He said that obligation could be disregarded only in relation to Iraq if the war was lawful under international and domestic law.
But the government's lawyer, Philip Sales, said the grounds submitted by the families did not disclose "an arguable case" which should go to a full hearing.
The judge agreed.
The families argue the decision to go to war because Iraq had weapons of mass destruction was illegal and based on lies.
Government lawyers had refused their request for a full public inquiry.
It is still possible for the families to renew their application for permission in the Court of Appeal.