engineering

Nagashima

Nagashima is a engineering topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Nagashima rather than just read about it. In short: Nagashima (長島) was a series of fortresses and fortifications controlled by the Ikkō-ikki, a sect of warrior monks in Japan's Sengoku period who opposed samurai rule. It was attacked and destroyed by Oda Nobunaga in the 1570s.

Key takeaways

Nagashima belongs to engineering; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Nagashima to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Nagashima from memory before moving on to harder problems.

Reference excerpt

Nagashima (長島) was a series of fortresses and fortifications controlled by the Ikkō-ikki, a sect of warrior monks in Japan's Sengoku period who opposed samurai rule. It was attacked and destroyed by Oda Nobunaga in the 1570s. This, combined with the surrender of the Ikki's other main fortress, Ishiyama Hongan-ji, several years later, ended the threat the Ikko-ikki posed to Nobunaga and other samurai conquerors. The fortress was situated on a swampy delta, on the border of Owari and Ise Provinces, at the point where three rivers converge, to the southwest of the modern-day city of Nagoya. Nagashima was in fact a number of smaller fortifications surrounding two primary buildings and not a single fortress. Nagashima Castle was built in 1555 by Ito Shigeharu, and seized by the Ikkō-ikki shortly afterwards, in much the same way they had seized a number of other daimyōs' holdings. The Ganshō-ji fortified monastery formed the second center of Nagashima's defense. At one time, the area may have been known as "Nanashima" or "seven islands". It is currently one island between the Kiso and Nagara Rivers, with Ise Bay at its southern tip. The Oda clan, which controlled nearby lands, was wary of the Ikki's growing power, and engaged them at Ogie Castle in 1569. The Ikki were victorious, and Nobunaga's brother Nobuoki was killed. Nobunaga returned to lay siege to the Ikki's fortress three times, before finally subduing it in 1574 with the help of the Kumano Suigun (Navy) under the control of the Kuki family. He set the wooden structure ablaze, and none of the fortress cathedral's 20,000 inhabitants escaped. According to the members of the Nagashima Historical Society, none of the main castle of Nagashima survived and its true location is unknown. What is believed to be the most probable location is now the site of a junior high school, which was identified in accordance to written descriptions of the area in the 16th century and what is believed to be an old moat. There is a map at the site, next to the school. The reconstructed castle gate was washed away during the Isewan Typhoon in 1959. Ganshōji was rebuilt some distance inland. A stone stupa was erected as a memorial to those killed in the burning of the fortress.

Worked examples

Example 1 — a first encounter with Nagashima

Start with the simplest possible case. Write down what Nagashima claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In engineering, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Nagashima before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Nagashima ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Nagashima

In research: Nagashima appears in engineering research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Nagashima in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Nagashima is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1555 establishments in Japan, 16th-century fortifications, Buildings and structures completed in 1555, so understanding it makes those chapters shorter.
In everyday life: Look for Nagashima outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Nagashima in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Nagashima means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Nagashima out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Nagashima in simple terms?

Why does Nagashima matter?

Because it connects several engineering ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Nagashima?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Nagashima.