25 April 1953

Francis Crick and James Watson publish “Molecular Structure of Nucleic Acids: A Structure for Deoxyribose Nucleic Acid” describing the double helix structure of DNA.

The double helix structure of DNA is the shape that the DNA molecule takes. DNA, or deoxyribonucleic acid, is the genetic material that carries the instructions for the development, functioning, and reproduction of all living organisms.

The double helix structure is made up of two strands of nucleotides that are twisted together in a helical shape. Each nucleotide is composed of a sugar molecule, a phosphate group, and a nitrogenous base. The nitrogenous bases in DNA are adenine (A), thymine (T), cytosine (C), and guanine (G).

The two strands of the double helix are held together by hydrogen bonds between the nitrogenous bases. Specifically, adenine always pairs with thymine, and cytosine always pairs with guanine. This base-pairing rule is known as complementary base pairing.

The double helix structure of DNA is important because it allows for the faithful replication of the genetic material during cell division. The complementary base pairing ensures that the sequence of nucleotides in the original DNA molecule is accurately preserved in the newly synthesized DNA molecule. Additionally, the double helix structure protects the genetic information from damage and allows for the efficient storage and retrieval of genetic information.

25 April 1898

The United States declares war on Spain.

On 25 April 1898, the United States Congress declared war upon Spain. The ensuing Spanish–American War resulted in a decisive victory for the United States, and arguably served as a transitional period for both nations. Spain saw its days of empire fade, as the United States saw the prospect of overseas empire emerge. The war was ended by the Treaty of Paris signed on December 10 that same year.

The Spanish–American War originated out of the Cuban War of Independence, launched in February 1895. For decades the United States had watched political developments on Cuba, with which it had extensive economic ties. Historians have long debated America’s intentions in becoming involved in the conflict. For a significant period during and after the war, selfless humanitarian interest in the fate of the Cuban people was accepted as the major impetus for the declaration of war. A supporting argument for this line of thinking is that yellow journalism created an inflammatory mood in the country and swayed public opinion to sympathize with Cuba. Recently this school of thinking has grown less popular. Many historians now believe that the United States was acting more out of its own self-interest, in particular to assist long-term goals of creating an Isthmian canal, and pursuing trade with China.

On February 15, 1898, an explosion aboard the USS Maine in Havana harbor killed 260 US personnel. Public opinion in the U.S., driven in part by the yellow journalism of William Randolph Hearst and Joseph Pulitzer, blamed Spain, though Spain has no reason for wanting to provoke the U.S. to intervene in Cuba’s war for independence, then more than three years old. The U.S. Congress passed legislation allocating an additional $50 million for the military on March 9 and on March 26 President William McKinley demanded that Spain end hostilities by October 1. Spain rejected McKinley’s proposal and objected to his interference. McKinley requested authorization from Congress to intervene in Cuba on April 11. Two days later the U.S. Congress by vote of 311 to 6 in the House and 42 to 35 in the Senate passed the Joint Resolution for Cuban independence, which both disavowed any intention of annexing Cuba and authorized the President to use military force to end hostilities between Spain and Cuba. An ultimatum to leave Cuba or face American military intervention was forwarded to Spain on April 20. The Spanish interpreted this ultimatum as declaration of war, even though it technically was not, dismissed the U.S. ambassador, and declared war. On April 22, the U.S. fleet set sail from Key West, Florida, to establish a blockade and prevent the Spanish from delivering supplies to its military forces in Cuba. The U.S. responded by declaring on April 25 that a state of war had existed since the 21st.

A bill declaring that war exists between the United States of America and the Kingdom of Spain.

Be it enacted by the Senate and House of Representatives of the United States of America in Congress assembled, First. That war be, and the same is hereby, declared to exist, and has existed since the twenty-first day of April, A.D. 1898, including said day, between the United States of America and the Kingdom of Spain.

Second. That the President of the United States be, and he hereby is, directed and empowered to use the entire land and naval forces of the United States and to call into the actual service of the United States the militia of the several States, to such extent as may be necessary to carry this act into effect.

Approved, April 25, 1898.


25 April 1916

Anzac Day is commemorated for the first time in Australia and New Zealand on the first anniversary of the landing at ANZAC Cove.

Anzac Day is a national day of remembrance in Australia and New Zealand that broadly commemorates all Australians and New Zealanders “who served and died in all wars, conflicts, and peacekeeping operations” and “the contribution and suffering of all those who have served”.

Observed on 25 April each year, Anzac Day was originally devised to honour the members of the Australian and New Zealand Army Corps who fought at Gallipoli against the Ottoman Empire during World War I. Anzac Day is also observed in the Cook Islands, Niue, Pitcairn Islands, and Tonga, and previously was a national holiday in Papua New Guinea and Samoa.

Anzac Day marks the anniversary of the first campaign that led to major casualties for Australian and New Zealand forces during the First World War. The acronym ANZAC stands for Australian and New Zealand Army Corps, whose soldiers were known as Anzacs. Anzac Day remains one of the most important national occasions of both Australia and New Zealand.

The first commemoration occurred in Adelaide, South Australia. It was the site of Australia’s first built memorial to the Gallipoli landing, unveiled by Governor-General Sir Ronald Munro Ferguson on “Wattle Day”, 7 September 1915, just over four months after the first landings. The monument was originally the centrepiece of the Wattle Day League’s Gallipoli Memorial Wattle Grove, later known as “Wattle Grove”, on Sir Lewis Cohen Avenue in the South Park Lands but in 1940 the Adelaide City Council moved the monument and its surrounding pergola to Lundie Garden, a lawned area off South Terrace near the junction with Anzac Highway. The original native pines and remnant seedlings of the original wattles still grow in “Wattle Grove”. Also in South Australia, Eight Hour Day, 13 October 1915, was renamed “Anzac Day” and a carnival was organised to raise money for the Wounded Soldiers Fund.

The date 25 April was officially named Anzac Day in 1916; in that year it was marked by a wide variety of ceremonies and services in Australia and New Zealand, including a commemorative march through London involving Australian and New Zealand troops. In New Zealand it was gazetted as a half-day holiday. Australian Great War battalion and brigade war diaries show that on this first anniversary, units including those on the front line, made efforts to solemnise the memory of those who were killed this day twelve months previously. A common format found in the war diaries by Australian and New Zealand soldiers for the day commenced with a dawn requiem mass, followed mid-morning with a commemorative service, and after lunch organised sports activities with the proceeds of any gambling going to Battalion funds. This occurred in Egypt as well.

In Queensland on 10 January 1916 Canon David John Garland was appointed the honorary secretary of the Anzac Day Commemoration Committee of Queensland at a public meeting which endorsed 25 April as be the date promoted as “Anzac Day” in 1916 and ever after. Devoted to the cause of a non-denominational commemoration that could be attended by the whole of Australian society, Garland worked amicably across all denominational divides, creating the framework for Anzac Day commemorative services. Garland is specifically credited with initiating the Anzac Day march, the wreath-laying ceremonies at memorials and the special church services, the two minutes silence, and the luncheon for returned soldiers. Garland intended the silence was used in lieu of a prayer to allow the Anzac Day service to be universally attended, allowing attendees to make a silent prayer or remembrance in accordance with their own beliefs. He particularly feared that the universality of the ceremony would fall victim to religious sectarian disputes.

In London, in the same year, over 2,000 Australian and New Zealand troops marched through the streets of the city. A London newspaper headline dubbed them “The Knights of Gallipoli”. Marches were held all over Australia in 1916; wounded soldiers from Gallipoli attended the Sydney march in convoys of cars, accompanied by nurses. Over 2,000 people attended the service in Rotorua. For the remaining years of the war, Anzac Day was used as an occasion for patriotic rallies and recruiting campaigns, and marches of serving members of the AIF were held in most cities. From 1916 onwards, in both Australia and New Zealand, Anzac memorials were held on or about 25 April, mainly organised by returned servicemen and school children in cooperation with local authorities.

Flags on the cenotaph in Wellington for the 2007 Dawn March. From left to right, the flags of New Zealand, the United Kingdom and Australia
Anzac Day was gazetted as a public holiday in New Zealand in 1920, through the Anzac Day Act, after lobbying by the New Zealand Returned Soldiers’ Association, the RSA. In Australia at the 1921 State Premiers’ Conference, it was decided that Anzac Day would be observed on 25 April each year. However, it was not observed uniformly in all the states.

25 April 1859

British and French engineers start work on the Suez Canal.

On 25th April, 1859, work started on the construction of the Suez Canal in Port Said, Egypt. Officially opened in November 1869, the 101 mile long canal is a vital trade route connecting the Mediterranean Sea to the Gulf of Suez in the Red Sea.

When the canal opened some ten years later, its construction had cost $100 million. The creation of the canal triggered the growth of settlements around the area of Suez. Previous to the commencement of the project, the arid territory had been largely uninhabited, but following the start of the construction more than 70,000 acres of land were brought under cultivation.

The Suez Canal was not the first attempt in history to connect the Mediterranean to the Red Sea. Canals had been constructed in the area in the thirteenth century BCE. During the Ptolemaic period of Ancient Egypt, a series of canals were used to facilitate trade through Egypt, however, over the course of the next thousand years they gradually fell into disrepair or were destroyed in military conflicts.The Suez Canal had a dramatic impact on world trade, allowing goods to be shipped across the globe in record time. In 1888, an international convention made the canal available for use by ships from any country.