The Dano-Swedish War of 1808-1809 brought Swedish troops streaming across the Norwegian border at multiple points. On April 15, 1808, one day after the 2nd Brigade crossed farther north, the Swedish 3rd Brigade under Colonel Bror Cederstrom pushed through from Tocksmark into the lake country around Rodenessjoen and Oymarksjoen. These long, narrow lakes running north-south created natural corridors for movement, and the Swedes quickly established outposts from Hemnes in the north down to their headquarters at Orje, where Cederstrom ordered barricades constructed. The goal was clear: secure the eastern approach to Christiania, modern-day Oslo.

Prince Christian August, commanding Norwegian forces, faced a dilemma. The Swedish breakthrough at Lier and their advance toward Kongsvinger demanded his attention, but he could not ignore the 3rd Brigade threatening to cut off his troops from behind. On April 20, he dispatched two companies under Captains Heyerdahl and Zarbell toward Hemnes. When rumors spread that the Swedes were advancing, Heyerdahl pulled his company back to Fetsund. Zarbell chose differently. He positioned his men west of the farm at Lund, near Hemnes Church, and refused to move. When Cederstrom ordered his forces to drive Zarbell out, they attacked repeatedly. Each time, they failed.

The Norwegian victory at Trangen in late April relieved pressure on Kongsvinger, freeing Christian August to reinforce Rodenes. On May 4, Major Andreas Samuel Krebs marched from Aurskog with three companies of Jagers, four grenadier companies, sharpshooters, and cavalry from the Akershusiske dragonregiment. That evening, Zarbell and his sharpshooters, joined by Lieutenant Hegge's 3rd Jager company, advanced on Swedish positions at Opsal. They attacked immediately but could not dislodge the 150 Swedes of the 1st Sodermanlands battalion holding the high ground at Krok farm. The river crossing at Opsal and the hilltop position beyond proved too strong.

On the morning of May 6, Krebs received orders from Prince Christian August to fall back. The withdrawal happened in silence, and the Norwegians slipped away without pursuit. But the fighting was not over. The next morning, Captain Fischer led sharpshooters of the 4th Jager company and two companies of the Nordenfjelske Regiment against Orje bridge. They quickly overwhelmed the Swedish outposts and advanced on the fortified bridgehead, defended by 120 men of the Dalbataljonen. Fischer paused to prepare for the final assault on the bridge. That moment of hesitation proved decisive. Swedish Captain Tornblad got his men across and ordered the bridge set ablaze. The flames rose, the timbers collapsed, and any Norwegian hope of crossing died with them.

The Battle of Rodenes ended without a decisive clash, yet it was a strategic Norwegian success. Though Swedish forces remained on Norwegian soil, their advance had been stopped cold. The dream of reaching Christiania by pushing through Smaalenenes Amt evaporated in those weeks of skirmishing among the lakes and forests. The Jagers who fought there received awards for their service. But no one was honored more than Lars Opsal, the farmer turned soldier whose sword with its silver booklet became a symbol of what ordinary Norwegians could achieve when their homeland was invaded.