In contrast to the peaceful human colonists of
Naboo, the native
Gungans are a proud warrior species. The amphibians have long maintained a huge standing army -- the
Gungan Grand Army -- as one of their proudest traditions. The martial nature of the Gungans has caused tension between the natives and the Naboo for centuries.
During the Trade Federation occupation of Naboo, the Gungan leader, Boss Nass, first thought the conflict to be entirely an outsider's affair. He did not believe the droid armies of the Trade Federation would find the submerged city of Otoh Gunga. Nass was wrong, and Otoh Gunga was overrun by invading droids. The Gungans retreated from their city, taking refuge in the Gungan Sacred Place hidden in the Naboo forests.
Queen Amidala of the Naboo surprised Nass by humbly requesting Gungan aid in fighting off the Trade Federation. This overture began to undo the centuries-long rift between the Naboo and the Gungans, and Boss Nass committed 2,000 of his soldiers to the effort of liberating Naboo.
The Gungans prefer technology that is harmonious with the ecology of their world. Their weaponry is no different. The Gungan Grand Army uses domesticated animals for transport -- swift kaadu speed Gungan scouts and cavaliers into combat, while hardy falumpasets and fambaas haul heavy weapons and shield generators into place. Gungans use the exotic, energetic plasma mined from Naboo's crust not only to power their cities, but also as ammunition for their weapons.
The Gungan forces held off the battle droid army long enough for Queen Amidala's resistance force to infiltrate Theed and launch their starfighter sources. The Gungans were nearly overrun, but the Naboo's Bravo Squadron was able to destroy the orbiting Droid Control Ship, thus deactivating the Trade Federation army.
The next day, the Grand Army and Augie's Great Municipal Band joined to form a massive Gungan victory parade through the streets of Theed.