[2][3] The long Alpine front, on the other hand, was entrusted to the Italian Volunteer Corps of Giuseppe Garibaldi, who was entrusted with the task of controlling the long stretch of border that divided Lombardy from Tyrol and Trentino, mainly through two penetration routes: the Passo dello Stelvio, to the north, and the Passo del Tonale, to the center.

By doing this, the Austrian commander in Tyrol, General Franz Kuhn von Kuhnenfeld replied to a telegram received on June 29, a few days after the Italian defeat at the Battle of Custoza, from Archduke Albrecht: Keep Tonale and Stelvio passages manned with permanent shooters, at the same time advance along these passes with mobile troops on Edolo, Tirano, Teglio, from there to wage a small war.

[2][3]The first action occurred at Tonale, where a first detachment was brought, which the Italians would have tried, in vain, to dislodge, at the battle of Vezza d'Oglio .

On the evening of July 3, a detachment of about fifty men had proceeded much farther on, on the Mortirolo Pass, to check for any connections between the volunteers from Valcamonica and those from Valtellina.

[2][3] However the Austrians were weakened and on July 11, at midnight, an Italian squad, led by Pietro Pedranzini from Bormio, began the ascent of the rugged Reit pass, to swoop by surprise on the first roadman of the Stelvio, capturing the entire detachment, 65 prisoners.