THIS WEEK IN HISTORY: FEBRUARY 23, 1836

The Siege of the Alamo Begins

alamo-siegeAlamo, (Spanish: “Cottonwood”) 18th-century Franciscan mission in San Antonio, Texas, U.S., that was the site of a historic resistance effort by a small group of determined fighters for Texan independence (1836) from Mexico.

The building was originally the chapel of the Mission San Antonio de Valero, which had been founded between 1716 and 1718 by Franciscans. Before the end of the century, the mission had been abandoned and the buildings fell into partial ruin. After 1801 the chapel was occupied sporadically by Spanish troops. Apparently, it was during that period that the old chapel became popularly known as “the Alamo” because of the grove of cottonwood trees in which it stood.

In December 1835, at the opening of the Texas Revolution (War of Texas Independence), a detachment of Texan volunteers, many of whom were recent arrivals from the United States, drove a Mexican force from San Antonio and occupied the Alamo. Some Texan leaders — including Sam Houston, who had been named commanding general of the Texas army the month before — counseled the abandonment of San Antonio as impossible to defend with the small body of troops available, but the rugged bunch of volunteers at the Alamo refused to retire from their exposed position. On February 23, 1836, a Mexican army, variously estimated at 1,800 to 6,000 men and commanded by General Antonio López de Santa Anna, arrived from south of the Rio Grande and immediately began a siege of the Alamo. Estimates of the size of the small defending force (including some later arrivals) usually vary between 183 and 189 men, though some historians believe that figure may have been larger. That force was commanded by Colonels James Bowie and William B. Travis and included the renowned frontiersman Davy Crockett. At the beginning of the siege, Travis dispatched “To the People of Texas & all Americans in the world” an impassioned letter requesting support (see primary source document: “Victory or Death” message from the Alamo). For 13 days the Alamo’s defenders held out, but on the morning of March 6 the Mexicans stormed through a breach in the outer wall of the courtyard and overwhelmed the Texan forces. Santa Anna had ordered that no prisoners be taken, and virtually all the defenders were slain (only about 15 persons, mostly women and children, were spared). The Mexicans suffered heavy casualties as well; credible reports suggest between 600 and 1,600 were killed and perhaps 300 were wounded.

Although the Texan defenders suffered defeat, the siege at the Alamo became for Texans a symbol of heroic resistance. On April 21, 1836, when Houston and a force of some 900 men routed 1,200 to 1,300 Mexicans under Santa Anna at the Battle of San Jacinto, the Texan forces shouted, “Remember the Alamo!” That popularized battle cry later was used by U.S. soldiers in the Mexican–American War (1846–48).

For many years after 1845 — the year that Texas was annexed by the United States — the Alamo was used by the U.S. Army for quartering troops and storing supplies. In 1883 the state of Texas purchased the Alamo, and in 1903 it acquired the title to the remainder of the old mission grounds. The Alamo and its adjacent buildings have been restored and are maintained as a state historic site. They are managed on a daily basis by the Daughters of the Republic of Texas (1891), a women’s organization composed of descendants of Texan pioneers. In 2015 the Alamo along with four other 18th-century Spanish missions nearby and a historic ranch to the southeast in Floresville were collectively designated a UNESCO World Heritage site.

“Alamo.” Britannica School. Encyclopædia Britannica, Inc., 2015. Web.

THIS WEEK IN HISTORY: FEBRUARY 14, 1946

ENIAC Unveiled

ENIACThe Electronic Numerical Integrator and Computer (ENIAC) was designed during World War II by J. Presper Eckert and John Mauchly at the University of Pennsylvania for the United States Army. It was the forerunner of Eckert and Mauchly’s UNIVAC, which was the first widely-available commercial computer. Because of the war, the University of Pennsylvania’s Moore School of Engineering had a contract with the United States Army to design an advanced machine that could perform military-related calculations, such as cannon trajectories. The machine, which came to be called ENIAC, was needed quickly, and the design team decided to use available materials and technology, such as vacuum tube processors and punched cards to store the program and data.

In 1941 when the project began, John Mauchly was a physicist who had recently joined the faculty and Presper Eckert was an engineering student. Also on the team was Arthur Burks, a mathematician and logic expert who was responsible for ENIAC’s circuitry. ENIAC contained 18,000 vacuum tubes and required 160,000 watts of power. It weighed thirty tons, and took up over 1,500 square feet. Using ten-digit decimal numbers, it could perform 5,000 additions or subtractions per second. It also multiplied, divided, and calculated square roots. Programming was originally provided by interconnected wiring, like a telephone switchboard. Later, it was refitted to use punched card programs.

The computer was dedicated in February 1946, and was used to compute the trajectories of artillery shells for the Army, Navy, and Air Force. It also performed calculations related to meteorology and to nuclear weapons research, including various radiation studies. ENIAC continued to operate until 1955. During its lifetime it demonstrated that electronic systems could be reliable as well as accurate, paving the way for future computers. But its design became the center of a legal controversy. In 1937, John Atanasoff, a physicist at Iowa State College  designed a computer with vacuum tube processors, binary numbers, serial calculation, punched cards for input and output, and memory consisting of condensers placing charges on rotating drums of Bakelite — a type of early plastic. Under Atanasoff’s faculty contract, the patent on anything that he invented would be held by the school — a common practice. However, when he asked Iowa State to patent his computer, the school refused.

By 1942, Atanasoff and Clifford Berry, a graduate student, built enough of the A-B-C computer — named for their initials — to calculate differential equations. Atanasoff then took up other World War II-related research and did not go back to the computer project. However, in December 1940, Atanasoff had met John Mauchly at a scientific meeting and invited him to Iowa to see the computer. The visit took place in June, 1941. Atanasoff demonstrated the A-B-C. Mauchly (who already had computer design experience) and Eckert went on to design and build ENIAC and to take out a patent on it. The ENIAC patent served as the basis for their later computers, EDVAC, BINAC, and UNIVAC, built by their own firm.

In 1950, Remington Rand bought their company, including all UNIVAC-related patents. By the 1960s, Remington Rand had become Sperry Rand. During that time a competitor, Honeywell, contacted Atanasoff and they decided to challenge the Sperry Rand patent. In court, Atanasoff’s case was based on his original design and on Mauchly’s visit to Iowa. Atanasoff’s machine was strictly a differential analyzer, and Mauchly countered that he had not stolen Atanasoff’s design. He contended that he had the main elements of his computer design before meeting with Atanasoff and seeing the A-B-C. Mauchly believed the design was flawed, though he was impressed with the performance, and he intended to build a general-purpose machine. Several scientists who had worked on ENIAC supported Atanasoff, while others supported Eckert and Mauchly. In 1973, the judge ruled in Atanasoff’s favor, declaring the ENIAC-UNIVAC patent invalid.

“ENIAC.” World of Invention. Gale, 2006. Science in Context. Web.