Their old diesel engines roaring, the Cold War-era battle tanks bobbed through the verdant Germany countryside as the Ukrainian commander radioed an order to his unit to fire. The gunners’ task was to aim and shoot the 105-millimeter cannon at green pop-up targets as far as 1,500 yards away.

“Fifteen of 17 is a very good result,” said Lt. Col. Marco Maulbecker, who oversees the tank training, referring to the number of targets hit by the crews on the first attempt. “Now we have to work on getting those targets faster.”

The exercise — a coordinated attack — was the culmination of a six-week course for the Ukrainians on how to use one of the latest additions to their country’s wartime arsenal — the Leopard 1A5s, the decommissioned German-made battle tanks that Germany and its NATO allies promised to Kyiv early this year after weeks of hesitation.

At the time, Germany was criticized for its dithering when it came to sending German-made tanks to Ukraine. The reluctance reflected Germany’s ambivalence about taking a military leadership role in Europe after World War II, but also the burdens on a German military that was chronically underfunded.

After the United States and other allies said they would send tanks, too, Germany agreed to send up to 18 modern Leopard 2A6 battle tanks to Ukraine. But ultimately, the bulk of its commitment — more than 100 additional tanks — were an obsolete model, the Leopard 1A5, the first 10 of which arrived in Ukraine last month.

The Leopard 1A5 is so old, in fact, that the German trainers had to rely on soldiers from the Dutch and Danish armies — where the model was used for longer — and former German tank drivers who trained back in the 1980s and 1990s. The last time the German army actually taught recruits on the system was in 2000.

Some of the trainers were civilians in their 50s or 60s who took a break from their day jobs to help. “They were really important in getting us going from a cold start,” said Colonel Maulbecker, who normally commands a battalion of modern tanks.

Despite its age, some experts and German officials say the Leopard 1A5 can be a useful stopgap. Its modern descendant, the Leopard 2A6, is vastly more expensive and even the small number donated to Ukraine had to be taken directly from the ranks of the German military, where the tanks are badly needed.

And just because the Leopard 1A5 is old does not mean that it can’t be effective, once the decommissioned stock is refurbished. It is comparable with but superior to the Soviet-built T-72 tanks, which Ukrainian forces also use.

It has night-vision capability, a weapons stabilization system and it can drive backward, which cannot be said for all of the older battle tanks currently seeing action in Ukraine, according to Brig. Gen. Andreas Marlow, who oversees Germany’s training program for the Ukrainians.

When the tank is used in the right context and on the right terrain, it can be highly effective in combat, said General Marlow, who was trained on the tanks as a young soldier.

Despite being generations behind the modern tanks Kyiv had asked for, the Leopard 1A5 has other advantages: It is easier to master, maintain and fix, and, General Marlow said, “Quantity plays a role, too.”

Given its slow planning and underfunding, the German army really had no other option when it came to donating significant number of tanks, noted Christian Mölling, a military expert at the German Council on Foreign Relations.

“Those Leopard 1 tanks are really not a bad option,” he said.

Many of the tanks had sat unused in warehouses around Europe until the German government gave the approval earlier this year for them to be donated to Ukraine. They were bought up by arms manufacturers, who are refurbishing the tanks at the expense of Germany and its allies.

Large spray-painted numbers identify the tanks, whose years of wear and decades of storage are evident from their scratches and dents. The insulation on the barrel of one of the tanks shown on a recent tour of the training area was held together by zip ties.

The Leopard 1A5 was an upgrade of older Leopard tank models, some of which were built as early as the 1960s, designed by a consortium that included Porsche. They were converted in the late 1980s and early 1990s, just as the German army was shrinking following the end of the Cold War.

The recent training, held at a former East German army base in Klietz, just 30 miles from what was the NATO border during the Cold War, is a key part of the European Union’s military assistance to Ukraine.

Germany, which is the second biggest donor of direct military aid to Ukraine, has trained 6,300 of the 10,000 Ukrainian troops it plans to train this year. The courses include infantry, sharpshooting, artillery and operating the various major weapon systems that Germany has provided. The German commitment is part of an E.U. program that aims to train 30,000 Ukrainian soldiers by end of next year.

In the current session, the Ukrainian tank commander was identified only by his call sign, Bassist, in keeping with Ukrainian military protocols. He said he wasn’t surprised when he saw older men among his trainers.

“In the end, if someone is a professional, it doesn’t matter how old he is,” he said.

The refurbished tanks that he and his colleagues trained on — a single cohort consists of roughly 50 soldiers and their commanders — were brought to Klietz by the Danes, who also cofinanced the donation of the Leopard 1A5s. Another 132 tanks, including specialized Leopard 1A5s used for salvage and instruction, will be sent to Ukraine in the coming year.

“Ukraine cannot grant us more than six weeks of training for understandable reasons, and we just try to make the best of it,” General Marlow said.

That means the Ukrainian tank crews train six days a week, but they hardly seemed to mind.

“It’s safe place and it’s quiet,” Bassist said after climbing out of the tank. “Just what you need when learning.”