Montessori schools were closed in Germany by the Nazi regime due to their perceived incompatibility with Nazi ideology. This marked a significant setback for the Montessori movement in Europe.

Maria Montessori left Italy due to increasing tensions with the Fascist government. Her outspoken views on education and peace clashed with the regime's agenda.

Montessori moved to Barcelona, Spain, where she continued to develop and promote her educational methods. However, the outbreak of the Spanish Civil War forced her to relocate again.

Montessori and her family settled in the Netherlands, where she continued her work in education. The Netherlands provided a relatively safe haven during the early years of World War II.

While in India to conduct teacher training, Maria Montessori and her son Mario were interned by the British government as Italian citizens during World War II. Despite the restrictions, she used her time to continue her research and develop her ideas on education for peace. She developed the concept of Education for Peace.