Rubuta ci gaba don wannan sakin layi - Ta haka Sweden ta riƙe, na ɗan lokaci, ikon manyan hanyoyin kasuwanci na Baltic har zuwa iyakokin masarautar; kuma karuwar kudaden shiga da ke haifar da wannan matsayi na umarni ya kasance na taimakon kayan aiki a farkon matakan yaƙin a Jamus, inda Gustavus ya tura sojojinsa a watan Yunin 1630. Gustavus, wanda daga baya aka kira shi "Zaki na Arewa" saboda ƙwarewarsa a matsayin kwamandan, ya shiga tsakani a bangaren Furotesta a yakin basasa na Jamus. Ta yin amfani da sababbin dabarun yaƙi kamar su makamai masu sauƙi da motsi da dakarun sojan doki, ya ci nasara mai ban mamaki a Yaƙin Breitenfeld a shekara ta 1631. A Yaƙin Lützen a ranar 6 ga Nuwamba, 1632, an kashe shi, kuma Sweden ta yi hasarar sarkinta mayaƙi. Yaƙin da kansa ba shi da nasara, amma bayan shekara biyu, yanayin ya canja a Nördlingen
, inda sojojin Imperial suka ci nasara a kan sojojin Protestant. Don hana Habsburgs daga cin nasarar yaƙin, Faransa, wacce ta riga ta ba da tallafi ga Sweden bayan Yarjejeniyar Bärwalde (1631), ta shiga tsakani a gefen Furotesta. Yaƙin ya ci gaba har tsawon shekaru har sai da aka cimma yarjejeniyar zaman lafiya a shekara ta 1648.