Q: This task involves annotating the answer type to a given question that involve some kind of complex reasoning (including numerical reasoning). Note that the questions require looking at more than one part of the passage to answer. There are 3 possible answer types (i) spans, (ii) numbers and (iii) dates. If the answer can be found in the passage, label it as "span". If the answer is a number, label as "number". Similarly, label "date" if you think the answer to the given question is a date.
Passage: On 15 August 1919, German border guards massacred ten Silesian civilians in a labour dispute at the Mysowice mine . The massacre sparked protests from the Silesian Polish miners, including a general strike of about 140,000 workers, and caused the First Silesian Uprising against German control of Upper Silesia. The miners demanded the local government and police become ethnically mixed to include both Germans and Poles. About 21,000 Germans soldiers of the Weimar Republic's Provisional National Army , with about 40,000 troops held in reserve, quickly put down the uprising. The army's reaction was harsh; and about 2,500 Poles were either hanged or executed by firing squad for their parts in the violence. Some 9,000 ethnic Poles sought refuge in the Second Polish Republic, taking along their family members. This came to an end when Allied forces were brought in to restore order, and the refugees were allowed to return later that year.
Question: What year were Polish refugees allowed to return after the First Silesian Uprising?
A:
date