arraign, a rain, a reign

Arraign or arraign ( one word ) means to summon before a court to answer an indictment, literally or figuratively--
They will arraign the suspect on Monday.
If they arraign him before the court of public opinion, he will be found guilty.

A rain or a rain ( two words, rhymes with arraign ) means a steady fall of water from the clouds, literally, or something else, figuratively--
News reports claim they had a rain of spiders in Australia.
He fell beneath a rain of blows, and lost consciousness.

A reign or a reign ( two words, rhymes with arraign ) means a span of time during which a monarch occupies a throne, or rules a country--
She will be remembered for a reign marked by conflict and economic depression.
The old queen has had a reign of more than fifty years; she may retire soon.

A rein or a rein ( two words, rhymes with arraign ) means a leather strap used to control an animal, literally, or, figuratively, a means of control restraint--
He held a rein in each hand, and checked the runaway horse.
The new rules are intended as a rein on some of the irresponsible behavior we've had lately.

Now that you know that, you can say--
"The queen, celebrating a reign of 60 years, was showered by a rain of confetti. The press refused to arraign her political conservatism, which often served as a rein on modernization."

rain, reign, rein

Rain or rain means the drops of water that fall from the sky--
Take an umbrella; it looks like rain.
He got soaked in the rain on the way home.
Do you think it'll rain?

Reign or reign ( rhymes with rain ) means the duration of the rule of a king or queen, or the royal power of ruling the state--
Queen Victoria's reign lasted more than sixty years.
The next sovereign to reign over England will be Prince Charles.

Rein or rein ( rhymes with rain ) means a leather strap used to control a horse or other animal. It may refer to the strap itself  ( a thing ), or to the capacity to control the animal with it--
He checked the horse with a light rein.
Rein in your horse!

Now that you know that, you can say--
"During the reign of the late king, Grandfather helped the prince rein in his horses, which were upset by the rain."

Note--"reins" is the plural ( more than one ) of "rein"-- 
Hold on to the reins, or the horse might bolt.
"Reins" is also an old-fashioned term for a person's kidneys--
Some ancient people believed that the reins were the seat of emotion. 
Note # 2--"arraign" means to make someone appear in court to answer a charge or indictment--
The judge will arraign him on Monday.
Not to be confused with "a rain"--
They were plagued by a rain of frogs.
Or "a rein"--
Try to keep a rein on your temper.
Or "a reign"--
She celebrated a reign of sixty years.