|There is more information available on this subject at Fougasse on the English Wikipedia.|
A fougasse is an improvised weapon that generally takes the appearance of a barrel or tube that is buried about a foot beneath the ground.
It has grenades or some other form of propellant in the bottom of it and can be filled with napalm ("fire" fougasses) or spent shell casings and various bits of metal ("shrapnel" fougasses). They can be remote detonated, sending fire and shrapnel upwards, cutting down anything above them for up to several meters. They are normally used to destroy ground targets, but can be used to take out low-flying craft.
Battle of Jericho VII
On February 12, 2535 the Master Chief and his team of Spartans used ten fougasses to destroy five Covenant Banshee fliers during an engagement on Jericho VII. He activated it when the fliers were still close to the ground on a strafing run so the blast hit them perfectly.
List of appearances