Well protected by fortifications of their famed cuadrilátero, Paraguayan soldiers surely exclaimed in wonder as they looked toward Brazilian lines on June 24, 1867. There, rising slowly in a hazy wintry sky, was a captive balloon held by two strong ascension ropes. An observer with a good spyglass could have seen in the basket two men who gazed intently at the Paraguayan positions. The aeronauts were James Allen of Rhode Island and Sergeant Major Roberto Adolfo Chodasiewicz, a Polish military engineer and cartographer. This first ascension by the smaller of two balloons proved that the brothers James and Ezra Allen, with the aid of Chodasiewicz, could succeed where a Frenchman, P. L. D. Doyen, had failed on December 14, 1866.