How did Poland assist Latvia in gaining control of Latgale?

During the Baltic War of Liberation (1918–1920), Poland provided critical military assistance to Latvia in its efforts to secure independence. Specifically, Latvian forces were aided by the Poles in driving the Bolsheviks out of southeastern Latvia, which allowed the Latvian government to gain control of the Latgale region. This cooperation was part of a broader period of conflict in which the Baltic states sought to fend off Soviet and German forces to establish their sovereignty.1