Evergreen date guide

What is celebrated on August 11?

See the observances and verified observance-history milestones attached to August 11. Each observance keeps its own source and date details.

Verified history

On this date in observance history

Today in history →

Selected observance milestones connected to this date, based on reviewed sources.

2026

Later action

Chad Independence Day

Confirmed continuing official observance of the August 11 independence anniversary.

2023

First observance

World Steelpan Day

Official Trinidad and Tobago government material states that the country celebrated World Steelpan Day for the first time on 11 August 2023.

2016

First observance

Mountain Day (山の日)

The 2014 amendment took effect from January 1, 2016, and current government history states that Mountain Day was established from 2016 on August 11.

About this date

What this date contains

3 observances

Each observance is shown once in this view, with its own source and scope details available on the guide page.

0 repeat predictably

0 use a fixed annual date and 0 follow a reusable calendar rule.

0 are edition-specific

These dates are shown only for the year or edition that has been confirmed.

2 have a country-specific scope

Country-specific observances are not presented as worldwide events.

3 have in-depth guides

These pages include reviewed meaning, history, activities, facts and FAQs.

Reviewed depth

Other in-depth guides on August 11

Source-backedFixed AnnualIn-depth guide

Chad Independence Day

11 August annually · Chad / national independence commemoration

Chadian government sources identify 11 August 1960 as the date of independence and continue the national commemoration in 2026.

Source-backedFixed AnnualIn-depth guide

Mountain Day (山の日)

11 August · Japan / statutory national holiday

Japan’s Act on National Holidays, as amended by Act No. 43 of 2014, establishes Mountain Day on 11 August and states its purpose as providing an opportunity to become familiar with mountain…

Source-backedFixed AnnualIn-depth guide

World Steelpan Day

11 August · United Nations / international observance

A/RES/77/316

Explore the mix

Topics represented on August 11

All topics →

Civic, Remembrance & History 1 Animals, Nature & Environment 1 Arts, Entertainment & Lifestyle 1

3 observances

All observances on this date

Source-backedFixed AnnualIn-depth guide

Chad Independence Day

11 August annually · Chad / national independence commemoration

Chadian government sources identify 11 August 1960 as the date of independence and continue the national commemoration in 2026.

Source-backedFixed AnnualIn-depth guide

Mountain Day (山の日)

11 August · Japan / statutory national holiday

Japan’s Act on National Holidays, as amended by Act No. 43 of 2014, establishes Mountain Day on 11 August and states its purpose as providing an opportunity to become familiar with mountain…

Source-backedFixed AnnualIn-depth guide

World Steelpan Day

11 August · United Nations / international observance

A/RES/77/316

How dates are selected

This page combines fixed annual dates, reusable calendar rules and year-specific dates confirmed for 2026. Variable or historical dates are included only when they are clearly supported.

Read the methodology →